- 标题
- 摘要
- 关键词
- 实验方案
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Pre-treatment for preventing degradation of measurement accuracy from speckle noise in speckle interferometry
摘要： Speckle interferometers, which can measure three-dimensional deformations with the same sensitivity in each direction of a three-dimensional axis, have been employed in the industry. However, the measurement results of a complex shape deformation using this method do not always produce a smooth phase map due to the influence of speckle noise. In this paper, this problem that occurs with speckle noise, which is included in the speckle pattern, is discussed. In addition, the solution to the problem concerning speckle noise is discussed. An idea for noise reduction is proposed by using a simple speckle pattern intensity distribution model based on the interferometry. It is confirmed that the proposed method can reduce the influence of speckle noise to 1/1000 of the light source wavelength.
关键词： Noise reduction,Influence of speckle noise,High resolution deformation measurement,ESPI (electronic speckle pattern interferometry)
更新于2025-09-23 15:23:52
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Device noise reduction for silicon nanowire field-effect-transistor based sensors by using a Schottky junction gate
摘要： The sensitivity of metal-oxide-semiconductor field-effect transistor (MOSFET) based nanoscale sensors is ultimately limited by noise induced by carrier trapping/detrapping processes at the gate oxide/semiconductor interfaces. We have designed a Schottky junction gated silicon nanowire field-effect transistor (SiNW-SJGFET) sensor, where the Schottky junction replaces the noisy oxide/semiconductor interface. Our sensor exhibits significantly reduced device noise, 2.1×10-9 V2μm2/Hz at 1 Hz, compared to reference devices with the oxide/semiconductor interface operated at both inversion and depletion modes. Further improvement can be anticipated by wrapping the nanowire by such a Schottky junction thereby eliminating all oxide/semiconductor interfaces. Hence, a combination of the low-noise SiNW-SJGFET device with a sensing surface of the Nernstian response limit holds promises for future high signal-to-noise ratio sensor applications.
关键词： Noise reduction,field-effect transistor,ion sensor,low frequency noise,schottky junction gate,silicon nanowire
更新于2025-09-23 15:23:52
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[IEEE 2018 17th International Conference on Ground Penetrating Radar (GPR) - Rapperswil, Switzerland (2018.6.18-2018.6.21)] 2018 17th International Conference on Ground Penetrating Radar (GPR) - Noise suppression of GPR data using Variational Mode Decomposition
摘要： Ground penetrating radar (GPR) has been used in the many aspects, such as civil engineering and the earth sciences. And the analysis and noise suppression of GPR data have always been the research focus. In this study, a new self-adaptive time-frequency decomposition tool called the variational mode decomposition (VMD) is introduced. We use the VMD method to derive a set of stationary sub-components, and based on the decomposition, we separate the valid signals and the components which are corresponded to the noise. One trace of GPR data are given to test the effect of the VMD decomposition, and the empirical mode decomposition (EMD) is also employed as a comparison. And a primary noise-suppression method based on the VMD scheme is also proposed. The application of the field GPR data further demonstrates the better performance of the proposed method in both noise suppression and the retention of geophysical events.
关键词： ground penetrating radar (GPR),mode decomposition,variational mode decomposition (VMD),noise reduction or suppression
更新于2025-09-23 15:23:52
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Adaptive Fuzzy Switching Noise Reduction Filter for Iris Pattern Recognition
摘要： Noise reduction is a necessary procedure for the iris recognition systems. This paper proposes an adaptive fuzzy switching noise reduction (AFSNR) filter to reduce noise for iris pattern recognition. The proposed low complexity AFSNR filter removes noise pixels by fuzzy switching between an adaptive median filter and the filling method. The threshold values of AFSNR filter are calculated on the basis of the histogram statistics of eyelashes, pupils, eyelids, and light illumination. The experimental results on the CASIA V3.0 iris database, with genuine acceptance rate equals 99.72%, show the success of the proposed method.
关键词： fuzzy switching median,iris normalization,eyelash detection,fuzzy weighted median,noise reduction,Iris pattern recognition
更新于2025-09-23 15:23:52
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[IEEE 2018 OCEANS - MTS/IEEE Kobe Techno-Ocean (OTO) - Kobe, Japan (2018.5.28-2018.5.31)] 2018 OCEANS - MTS/IEEE Kobe Techno-Oceans (OTO) - A Speed Measurement Method Using AUV Radiated Noise Spectrum
摘要： The noise produced by a motor can be easily controlled because its speed is from 0 to 1000 rpm. The noise of a motor is mainly caused by the interaction between the stator and rotor, and the noise can be reduced by controlling the speed of the motor. In this paper, we use a motor to produce noise and control it by a computer. The motor is driven by a computer and the noise is measured by a microphone. The computer controls the speed of the motor and the noise is reduced.
关键词： noise reduction,motor noise,speed control,computer control
更新于2025-09-23 15:22:29
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Time–frequency-based non-harmonic analysis to reduce line-noise impact for LIGO observation system
摘要： Gravitational waves (GWs) are the subjects of a new type of space observation that is expected to reveal new information on the early universe, neutron stars, and black holes. To reduce the impact of the widely used notch filter on GW observations, we propose the use of non-harmonic analysis (NHA) for the high-accuracy visualization of GWs. A simulated signal is used to compare the results obtained using short-time Fourier transform, Hilbert spectrum analysis, Hilbert–Huang transformation, and NHA. We demonstrate that NHA exhibits superior performance. In addition, we verify the analytical precision of NHA using actual data measured by the Laser Interferometer Gravitational-Wave Observatory (LIGO). We found that the high time–frequency resolution of NHA and the small influence that the analysis window has on this technique facilitate effective quantitative analysis, even for LIGO signals containing mixing noise. In addition, we achieve GW visualization up to the noise limit without using a notch filter.
关键词： Noise reduction,Non-harmonic analysis,Gravitational wave
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Speckle Noise Reduction of Time Series Sar Images Based on Wavelet Transform and Kalman Filter
摘要： Synthetic Aperture Radar (SAR) imaging systems can provide valuable sources of earth observation data for various applications. Speckle noise reduction of images produced by these systems is a challenging issue. In this paper, a novel method is proposed for reducing the speckle noise from time series SAR images. This method is mainly based on wavelet transform and Kalman filter. The proposed method is applied to a time series SAR images acquired by Sentinel-1 over Tehran, Iran. To demonstrate the performance of the proposed method, both qualitative and quantitative evaluations are reported compared to those of conventional speckle filtering methods. The experimental results show the good performance and efficiency of the proposed method for the speckle reduction of multitemporal SAR images. As well, the results show that the proposed method can preserve the major edge structures and the spatial resolution while reducing the time of processing.
关键词： wavelet transform,speckle noise reduction,kalman filter,Time series SAR images
更新于2025-09-23 15:21:21
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Fast non-local means noise reduction algorithm with acceleration function for improvement of image quality in gamma camera system: a phantom study
摘要： Gamma-ray images generally suffer from a lot of noise because of low photon detection in the gamma camera system. The purpose of this study is to improve the image quality in gamma-ray images using a gamma camera system with a fast nonlocal means (FNLM) noise reduction algorithm with an acceleration function. The designed FNLM algorithm is based on local region considerations, including the Euclidean distance in the gamma-ray image and use of the encoded information. To evaluate the noise characteristics, the normalized noise power spectrum (NNPS), contrast-to-noise ratio (CNR), and coefficient of variation (COV) were used. According to the NNPS result, the lowest values can be obtained using the FNLM noise reduction algorithm. In addition, when the conventional methods and the FNLM noise reduction algorithm were compared, the average CNR and COV using the proposed algorithm were approximately 2.23 and 7.95 times better than those of the noisy image, respectively. In particular, the image-processing time of the FNLM noise reduction algorithm can achieve the fastest time compared with conventional noise reduction methods. The results of the image qualities related to noise characteristics demonstrated the superiority of the proposed FNLM noise reduction algorithm in a gamma camera system.
关键词： Medical application,Noise reduction algorithm,Evaluation of image quality,Total variation noise reduction method,Gamma camera system
更新于2025-09-23 15:19:57
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Spatial squeezing in bright twin beams generated with four-wave mixing: Constraints on characterization with an electron-multiplying charge-coupled-device camera
摘要： The observation of spatial quantum noise reduction, or spatial squeezing, with a large number of photons can lead to a significant advantage in quantum imaging and quantum metrology due to the scaling of the signal-to-noise ratio with the number of photons. Here we present a systematic study of the limiting factors that play a role on the measurement of spatial squeezing with an electron-multiplying charge-coupled device (EMCCD) camera in the limit of bright quantum states of light generated with a four-wave mixing process in an atomic vapor cell. We detect a total number of photons per beam of the order 108 in 1 μs pulses, which corresponds to a photon flux per beam of the order of 1014 photons per second. We then investigate the role of different parameters, such as cell temperature, pump power, laser detunings, scattered pump background noise, and timing sequences for the image acquisition with the EMCCD camera, on the level of spatial squeezing. We identify critical parameters to obtain an optimum squeezing level and demonstrate that for bright beams it is essential to acquire images at a rate fast enough to overcome the effect of classical technical noise.
关键词： spatial squeezing,atomic vapor cell,quantum imaging,spatial quantum noise reduction,quantum metrology,four-wave mixing,EMCCD camera
更新于2025-09-12 10:27:22
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Pulse Compressed Time Domain Multiplexed Fiber Bragg Grating Sensor: A Comparative Study
摘要： This paper experimentally demonstrates the feasibility of improving the sensing performance of fiber Bragg grating (FBG)-based point sensors by deploying two pulse coding techniques, simplex coding (SSC), and Golay complementary codes (GCC). The two techniques are separately combined with the conventional time-domain multiplexed FBG (TDM-FBG) interrogation sensor, and their results are compared with respect to the conventional single pulse interrogation technique. Consistently with the theory, for both the coding techniques, we have confirmed that the signal-to-noise ratio improved proportionally to the code length. In details, for both the techniques, the signal-to-noise improvement ratio of two FBGs located after around 16.35 km of fiber has significantly increased up to about 6 dB. Furthermore, the decoded signals from both techniques conserve their original spatial properties, confirming the successfulness of Hadamard transform and Golay auto-correlation calculations. Our experimental analysis confirms the simplex codes with their significant noise reduction ability, which is translated into well formed and accurate mean amplitude calculations. Moreover, the analysis of TDM-FBG-based GCCs have confirmed the unique properties of the auto-correlation process to increase the FBG signals up to around 128 times compared with the single pulse case.
关键词： simplex pulse coding,Hadamard transform,TDM-FBG,auto-correlation,SSC,Golay complementary codes (GCC),signal-to-noise-ratio,Noise reduction
更新于2025-09-10 09:29:36