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Using Pearson’s System of Curves to Approximate the Distributions of the Difference between Two Correlated Estimates of Signal-to-Noise Ratios: The Cases of Bivariate Normal and Bivariate Lognormal Distributions
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作者 Mohamed M. Shoukri 《Open Journal of Statistics》 2024年第3期207-227,共21页
Background: The signal-to-noise ratio (SNR) is recognized as an index of measurements reproducibility. We derive the maximum likelihood estimators of SNR and discuss confidence interval construction on the difference ... Background: The signal-to-noise ratio (SNR) is recognized as an index of measurements reproducibility. We derive the maximum likelihood estimators of SNR and discuss confidence interval construction on the difference between two correlated SNRs when the readings are from bivariate normal and bivariate lognormal distribution. We use the Pearsons system of curves to approximate the difference between the two estimates and use the bootstrap methods to validate the approximate distributions of the statistic of interest. Methods: The paper uses the delta method to find the first four central moments, and hence the skewness and kurtosis which are important in the determination of the parameters of the Pearsons distribution. Results: The approach is illustrated in two examples;one from veterinary microbiology and food safety data and the other on data from clinical medicine. We derived the four central moments of the target statistics, together with the bootstrap method to evaluate the parameters of Pearsons distribution. The fitted Pearsons curves of Types I and II were recommended based on the available data. The R-codes are also provided to be readily used by the readers. 展开更多
关键词 signal-to-noise ratio Bivariate Distributions Bootstrap Methods Delta Method Pearson System of Curves
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Influence of the nonlinear propagation effect on the optical signal-to-noise ratio of 400G optical fiber communication systems 被引量:3
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作者 秦华强 肖晓晟 《Chinese Optics Letters》 SCIE EI CAS CSCD 2017年第3期78-82,共5页
The influence of the nonlinear propagation effect on three 400 Gb/s/ch (400G) optical fiber communication systems with typical modulation formats, dual-carrier 16-quadrature amplitude modulation (16QAM), single-ca... The influence of the nonlinear propagation effect on three 400 Gb/s/ch (400G) optical fiber communication systems with typical modulation formats, dual-carrier 16-quadrature amplitude modulation (16QAM), single-carrier 16QAM (single-16QAM), and four-carrier quadrature phase-shift keying, are investigated. The received optical signal-to-noise ratio (OSNR), affected by the nonlinear interference noise together with the amplified spontaneous emission noise, are compared with three 400G systems and a standard 100 Gb/s/ch system by numerical simulations. Both single channel and multichannel cases are considered. Single-16QAM is found to have the best OSNR among those modulation formats. 展开更多
关键词 MODULATION Nonlinear optics optical communication optical fibers optical signal processing Phase shift Phase shift keying Quadrature amplitude modulation Quadrature phase shift keying Signal to noise ratio
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Acquisition Practice of High Signal-to-Noise Ratio in YTB Block of Sichuan Basin
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作者 Jun Wu Jiangli Chen +5 位作者 Zhong Li Zengyou Wu Hong Liu Yiwei Li Yong Tang Junguo Du 《Journal of Geoscience and Environment Protection》 2023年第6期229-236,共8页
YTB block in Sichuan basin is a favorable area to exploit oil and gas in shallow tight rock. 3D seismic project of this zone has two characteristics. Firstly, it has high requirements for the tolerance rate of the con... YTB block in Sichuan basin is a favorable area to exploit oil and gas in shallow tight rock. 3D seismic project of this zone has two characteristics. Firstly, it has high requirements for the tolerance rate of the construction process and the acquisition of high signal-to-noise ratio seismic data;Second, there are widely obstacles and noises that lead to difficult acquisition construction organization. In acquisition practice, high signal-to-noise ratio seismic data was obtained by reasonable design of construction scheme, optimization of excitation parameters, improvement of receiving conditions and optimization of obstacle crossing observation system. . 展开更多
关键词 Tight Oil and Gas Tolerance Rate High signal-to-noise ratio OBSTACLE
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Optimizing Optical Attocells Positioning of Indoor Visible Light Communication System
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作者 Mohammed S.M.Gismalla Asrul I.Azmi +5 位作者 Mohd R.Salim Farabi Iqbal Mohammad F.L.Abdullah Mosab Hamdan Muzaffar Hamzah Abu Sahmah M.Supa’at 《Computers, Materials & Continua》 SCIE EI 2023年第2期3607-3625,共19页
Visible light communication(VLC),which is a prominent emerging solution that complements the radio frequency(RF)technology,exhibits the potential to meet the demands of fifth-generation(5G)and beyond technologies.The ... Visible light communication(VLC),which is a prominent emerging solution that complements the radio frequency(RF)technology,exhibits the potential to meet the demands of fifth-generation(5G)and beyond technologies.The random movement of mobile terminals in the indoor environment is a challenge in the VLC system.The model of optical attocells has a critical role in the uniform distribution and the quality of communication links in terms of received power and signal-to-noise ratio(SNR).As such,the optical attocells positions were optimized in this study with a developed try and error(TE)algorithm.The optimized optical attocells were examined and compared with previous models.This novel approach had successfully increased minimum received power from−1.29 to−0.225 dBm,along with enhanced SNR performance by 2.06 dB.The bit error rate(BER)was reduced to 4.42×10−8 and 6.63×10−14 by utilizing OOK-NRZ and BPSK modulation techniques,respectively.The optimized attocells positions displayed better uniform distribution,as both received power and SNR performances improved by 0.45 and 0.026,respectively.As the results of the proposed model are optimal,it is suitable for standard office and room model applications. 展开更多
关键词 Visible light communication(VLC) optical attocell received power signal-to-noise ratio(SNR) bit error rate(BER) coefficient of variation(CV)
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Extraordinary transmission and reflection in PT-symmetric two-segment-connected triangular optical waveguide networks with perfect and broken integer waveguide length ratios 被引量:1
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作者 Jia-Ye Wu Xu-Hang Wu +1 位作者 Xiang-Bo Yang Hai-Ying Li 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第10期367-375,共9页
By adjusting the waveguide length ratio, we study the extraordinary characteristics of electromagnetic waves propagating in one-dimensional(1D) parity-time-symmetric(PT-symmetric) two-segment-connected triangular opti... By adjusting the waveguide length ratio, we study the extraordinary characteristics of electromagnetic waves propagating in one-dimensional(1D) parity-time-symmetric(PT-symmetric) two-segment-connected triangular optical waveguide networks with perfect and broken integer waveguide length ratios respectively. It is found that the number and the corresponding frequencies of the extremum spontaneous PT-symmetric breaking points are dependent on the waveguide length ratio. Near the extremum breaking points, ultrastrong extraordinary transmissions are created and the maximal can arrive at, respectively, 2.4079 × 10^14 and 4.3555 × 10^13 in both kinds of networks. However, bidirectional invisibility can only be produced by the networks with broken integer waveguide length ratio, whose mechanism is explained in detail from the perspective of photonic band structure. The findings of this work can be useful optical characteristic control in the fabrication of PT-symmetric optical waveguide networks, which possesses great potential in designing optical amplifiers,optical energy saver devices, and special optical filters. 展开更多
关键词 parity-time symmetry optical WAVEGUIDE network INTEGER broken ratios
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Effective DOA Estimation Under Low Signal-to-Noise Ratio Based on Multi-Source Information Meta Fusion 被引量:2
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作者 Yun Wu Xiukun Li Zhimin Cao 《Journal of Beijing Institute of Technology》 EI CAS 2021年第4期377-396,共20页
Efficiently performing high-resolution direction of arrival(DOA)estimation under low signal-to-noise ratio(SNR)conditions has always been a challenge task in the literatures.Obvi-ously,in order to address this problem... Efficiently performing high-resolution direction of arrival(DOA)estimation under low signal-to-noise ratio(SNR)conditions has always been a challenge task in the literatures.Obvi-ously,in order to address this problem,the key is how to mine or reveal as much DOA related in-formation as possible from the degraded array outputs.However,it is certain that there is no per-fect solution for low SNR DOA estimation designed in the way of winner-takes-all.Therefore,this paper proposes to explore in depth the complementary DOA related information that exists in spa-tial spectrums acquired by different basic DOA estimators.Specifically,these basic spatial spec-trums are employed as the input of multi-source information fusion model.And the multi-source in-formation fusion model is composed of three heterogeneous meta learning machines,namely neural networks(NN),support vector machine(SVM),and random forests(RF).The final meta-spec-trum can be obtained by performing a final decision-making method.Experimental results illus-trate that the proposed information fusion based DOA estimation method can really make full use of the complementary information in the spatial spectrums obtained by different basic DOA estim-ators.Even under low SNR conditions,promising DOA estimation performance can be achieved. 展开更多
关键词 direction of arrival(DOA) signal-to-noise ratio(SNR) information fusion meta-learn-ing spatial spectrum
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Rare Earth Doped Optical Fibers for Temperature Sensing Utilizing Ratio-Based Technology 被引量:1
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作者 王玉田 耿丽琨 《Journal of Rare Earths》 SCIE EI CAS CSCD 2006年第z2期171-174,共4页
A new and practical fluorescence temperature detecting system based on fluorescence intensity ratio was proposed . The background theory of fluorescence intensity-ratio method was presented simply. And the characters ... A new and practical fluorescence temperature detecting system based on fluorescence intensity ratio was proposed . The background theory of fluorescence intensity-ratio method was presented simply. And the characters of rare earth doped samples were detailed. The erbium-doped fiber was chosen as the sensing element. The energy levels of 2H11/2 and 4S3/2 are responsible for the emission of radiation at approximately 530 and 555 nm. The erbium-doped (960 ppm) fiber of length 20 cm and core diameter 3.2μm was used as the sensing part. A silica photodiode transfers the fluorescence signal to electric signal, then the ratio of the average of the two different signals was calculated by the computer and the temperature was obtained. The ratio R of the intensity resulting from the transition between the two levels varies proportionly with temperature interval from 293 K to 373 K. The sensitivity of the sensor is approximately 0.05 K-1. 展开更多
关键词 fluorescence intensity ratio rare-earth doped material temperature detecting optical fiber
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An innovative detection method of high frequency BPSK signal with low signal-to-noise ratio 被引量:2
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作者 石硕 徐立振 +1 位作者 顾学迈 张宏莉 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2012年第6期93-99,共7页
Based on chaotic oscillator system, this paper proposes a novel method on high frequency low signal- to-noise ratio BPSK( Binary Phase Shift Keying) signal detection. Chaotic oscillator system is a typical non-lin- ... Based on chaotic oscillator system, this paper proposes a novel method on high frequency low signal- to-noise ratio BPSK( Binary Phase Shift Keying) signal detection. Chaotic oscillator system is a typical non-lin- ear system which is sensitive to periodic signals and immune to noise at the same time. Those properties make it possible to detect low signal-to-noise ratio signals. The BPSK signal is a common signal type which is widely used in modern communication. Starting from the analysis of advantages of chaotic, os~.illator system and signal features of the BPSK signal, we put forward a unique method that can detect low signar-to-noise ratio BPSK sig- nals with high frequency. The simulation results show that the novel method can dclct.t low signal-to-noise ratio BPSK signals with frequency in an order of magnitude of l0s Hz, and the input Signal-to-Noise Ratio threshold can be -20 dB. 展开更多
关键词 low signal-to-noise ratio signal detection chaotic oscillator system Binary Phase Shift Keying high frequency
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Epiretinal membrane related vascular changes in diabetic eyes evaluated with optical coherence tomography angiography
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作者 Umay Güvenç GünerÜney +3 位作者 NurtenÜnlü Mehmet Akif Acar Dicle Hazırolan Özlem Candan 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2023年第9期1503-1511,共9页
AIM:To evaluate the retinochoroidal microvascular circulation and anatomical structure of diabetic and nondiabetic patients with epiretinal membrane(ERM)with the help of optical coherence tomography angiography(OCT-A)... AIM:To evaluate the retinochoroidal microvascular circulation and anatomical structure of diabetic and nondiabetic patients with epiretinal membrane(ERM)with the help of optical coherence tomography angiography(OCT-A)and compare them with healthy control subjects.METHODS:In this prospective,cross-sectional study,a total of 165 eyes were evaluated,including 50 eyes of patients with diabetic ERM,54 eyes of idiopathic ERM(iERM)patients,and 61 eyes of healthy controls.Macula and disc angiography was performed by OCT-A.Macular vessel density(VD)ratio was evaluated by dividing the VD of the foveal region by the VD of the parafoveal region.Statistical calculations were evaluated at the 95%confidence interval.RESULTS:Macula superficial VD values of ERM cases were lower than that in the control group,while foveal VD was higher in ERM cases.Macula deep VD values of ERM cases were lower in all quadrants,except the fovea.The width of the foveal avascular zone(FAZ)area was significantly lower in the ERM groups,and the FAZ width was lowest in iERM group.Macula superficial VD ratio was significantly higher in the ERM groups,but there was no significant difference between ERM groups.Macula deep VD ratio was significantly higher in the iERM group than in the control group.CONCLUSION:Diabetic and idiopathic ERMs differ in their mechanism of formation and clinical presentation,as well as their effect on retinal vascular structures.If the relationship of increase of retinal thickness with vascular integrity can be demonstrated with OCT-A,then,OCT-A can be used as a guide for ERM prognosis. 展开更多
关键词 diabetic macular edema epiretinal membrane macula vessel density ratio optical coherence tomography angiography
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Signal-to-noise ratio of lensless ghost interference with thermal incoherent light 被引量:1
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作者 张二峰 戴宏毅 陈平形 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第2期229-234,共6页
Factors influencing the signal-to-noise ratio (SNR) of lensless ghost interference with thermal incoherent light are investigated. Our result shows that the SNR of lensless ghost interference is related to the trans... Factors influencing the signal-to-noise ratio (SNR) of lensless ghost interference with thermal incoherent light are investigated. Our result shows that the SNR of lensless ghost interference is related to the transverse length of the object, the position of the object in the imaging system and the transverse size of the light source. Furthermore, the effects of these factors on the SNR are discussed in detail by numerical simulations. 展开更多
关键词 ghost interference ghost imaging signal-to-noise ratio
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Noises and Signal-to-Noise Ratio of Nanosize EIS and ISFET Biosensors 被引量:2
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作者 Lusine Gasparyan Ilya Mazo +1 位作者 Vahan Simonyan Ferdinand Gasparyan 《Open Journal of Biophysics》 2020年第1期1-12,共12页
The results of comparative theoretical analyzes of the behavior of internal low-frequency noises, signal-to-noise ratio and sensitivity to DNA molecules for EIS and ISFET based nanosize biosensors are presented. It is... The results of comparative theoretical analyzes of the behavior of internal low-frequency noises, signal-to-noise ratio and sensitivity to DNA molecules for EIS and ISFET based nanosize biosensors are presented. It is shown that EIS biosensor is more sensitive to the presence of DNA molecules in aqueous solution than ISFET sensor. Internal electrical noises level decreases with the increase of concentration of DNA molecules in aqueous solution. In the frequency range 10&minus;3 - 103 Hz noises level for EIS sensor about in three orders is higher than for ISFET sensor. In the other hand, signal-to-noise ratio for capacitive EIS biosensor is much higher than for ISFET sensor. 展开更多
关键词 BIOSENSOR Noise Sensitivity signal-to-noise ratio
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Influence of signal-to-noise ratio on accuracy of spectral analysis by near infrared spectroscopy 被引量:1
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作者 ZHUANG Xin-gang SHI Xue-shun +3 位作者 LIU Hong-bo LIU Chang-ming ZHANG Peng-ju WANG Heng-fei 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2020年第3期211-216,共6页
As one of the important indicators of spectrometer,signal-to-noise ratio(SNR)reflects the ability of spectrometer to detect weak signals.To investigate the influence of SNR on the prediction accuracy of spectral analy... As one of the important indicators of spectrometer,signal-to-noise ratio(SNR)reflects the ability of spectrometer to detect weak signals.To investigate the influence of SNR on the prediction accuracy of spectral analysis,we first introduce the major factors affecting the spectral SNR.Taking green tea as an example,the influence of spectral SNR on the prediction accuracy of the origin identification model is analyzed by experiments.At the same time,the relationship between the spectral SNR and prediction accuracy of spectral analysis model is fitted.Based on this,the common methods for improving the spectral SNR are discussed.The results show that the accuracy of the prediction set model first decreases slowly,then decreases linearly,and finally tends to be flat as the spectral SNR decreases.Through calculation,in order to achieve the prediction accuracy of prediction model reaching 90%and 85%,the spectral SNR is required to be higher than 23.42 dB and 21.16 dB,respectively.The overall results provide certain parameters support for the development of new online analytical spectroscopic instruments,especially for the technical indicators of SNR. 展开更多
关键词 near infrared spectroscopy signal-to-noise ratio(SNR) partial least squares(PLS) spectral analysis green tea
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Refined Anam-Net:Lightweight Deep Learning Model for Improved Segmentation Performance of Optic Cup and Disc for Glaucoma Diagnosis
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作者 Khursheed Aurangzeb Syed Irtaza Haider Musaed Alhussein 《Computers, Materials & Continua》 SCIE EI 2024年第7期1381-1405,共25页
In this work,we aim to introduce some modifications to the Anam-Net deep neural network(DNN)model for segmenting optic cup(OC)and optic disc(OD)in retinal fundus images to estimate the cup-to-disc ratio(CDR).The CDR i... In this work,we aim to introduce some modifications to the Anam-Net deep neural network(DNN)model for segmenting optic cup(OC)and optic disc(OD)in retinal fundus images to estimate the cup-to-disc ratio(CDR).The CDR is a reliable measure for the early diagnosis of Glaucoma.In this study,we developed a lightweight DNN model for OC and OD segmentation in retinal fundus images.Our DNN model is based on modifications to Anam-Net,incorporating an anamorphic depth embedding block.To reduce computational complexity,we employ a fixed filter size for all convolution layers in the encoder and decoder stages as the network deepens.This modification significantly reduces the number of trainable parameters,making the model lightweight and suitable for resource-constrained applications.We evaluate the performance of the developed model using two publicly available retinal image databases,namely RIM-ONE and Drishti-GS.The results demonstrate promising OC segmentation performance across most standard evaluation metrics while achieving analogous results for OD segmentation.We used two retinal fundus image databases named RIM-ONE and Drishti-GS that contained 159 images and 101 retinal images,respectively.For OD segmentation using the RIM-ONE we obtain an f1-score(F1),Jaccard coefficient(JC),and overlapping error(OE)of 0.950,0.9219,and 0.0781,respectively.Similarly,for OC segmentation using the same databases,we achieve scores of 0.8481(F1),0.7428(JC),and 0.2572(OE).Based on these experimental results and the significantly lower number of trainable parameters,we conclude that the developed model is highly suitable for the early diagnosis of glaucoma by accurately estimating the CDR. 展开更多
关键词 Refined Anam-Net parameter tuning deep learning optic cup optic disc cup-to-disc ratio glaucoma diagnosis
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Measurements of NO_2 mixing ratios with topographic target light scattering-differential optical absorption spectroscopy system and comparisons to point monitoring technique
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作者 王杨 李昂 +6 位作者 谢品华 曾议 王瑞斌 陈浩 裴显 刘建国 刘文清 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第11期285-290,共6页
A topographic target light scattering-differential optical absorption spectroscopy ('IbTaL-DOA~) system is de- veloped for measuring average concentrations along a known optical path and studying surface-near distr... A topographic target light scattering-differential optical absorption spectroscopy ('IbTaL-DOA~) system is de- veloped for measuring average concentrations along a known optical path and studying surface-near distributions of atmospheric trace gases. The telescope of the ToTaL-DOAS system points to targets which are located at known dis- tances from the measurement device and illuminated by sunlight. Average concentrations with high spatial resolution can be retrieved by receiving sunlight reflected from the targets, A filed measurement of NO2 concentration is performed with the ToTaL-DOAS system in Shijiazhuang in the autumn of 2011. The measurement data are compared with con- centrations measured by the point monitoring technique at the same site. The results show that the ToTaL-DOAS system is sensitive to the variation of NO2 concentrations along the optical path. 展开更多
关键词 atmospheric optics target light scattering-differential optical absorption spectroscopy(ToTaL-DOAS) atmospheric trace gas averaging mixing ratio
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Enhancement of signal-to-noise ratio of ultracold polar NaCs molecular spectra by phase locking detection
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作者 王文浩 刘文良 +6 位作者 武寄洲 李玉清 王晓锋 刘艳艳 马杰 肖连团 贾锁堂 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第12期227-231,共5页
We report a method of high-sensitively detecting the weak signal in photoassociation (PA) spectra of ultracold NaCs molecules by phase sensitive-demodulated trap-loss spectra of Na atoms from a photomultiplier tube.... We report a method of high-sensitively detecting the weak signal in photoassociation (PA) spectra of ultracold NaCs molecules by phase sensitive-demodulated trap-loss spectra of Na atoms from a photomultiplier tube. We find that the signal-to-noise ratio (SNR) of the PA spectra is strongly dependent on the integration time and the sensitivity of the lock-in amplifier, and our results show reasonable agreement with the theoretical analyses of the SNR with the demodulation parameters. Meanwhile, we investigate the effect of the interaction time of the PA laser with the colliding Na-Cs atom pairs on the SNR of the PA spectra. The atom loss rate is dependent on both the PA-induced atom loss and the loading of the MOT. The high-sensitive detection of the excited ultracold NaCs molecules lays a solid foundation for further study of the formation and application of ultracold NaCs molecules. 展开更多
关键词 ultracold NaCs molecules PHOTOASSOCIATION high-resolution spectroscopy signal-to-noise ratio
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Signal-to-noise ratio of Raman signal measured by multichannel detectors
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作者 Xue-Lu Liu Yu-Chen Leng +2 位作者 Miao-Ling Lin Xin Cong Ping-Heng Tan 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第9期31-44,共14页
Raman spectroscopy has been widely used to characterize the physical properties of two-dimensional materials(2DMs).The signal-to-noise ratio(SNR or S/N ratio)of Raman signal usually serves as an important indicator to... Raman spectroscopy has been widely used to characterize the physical properties of two-dimensional materials(2DMs).The signal-to-noise ratio(SNR or S/N ratio)of Raman signal usually serves as an important indicator to evaluate the instrumental performance rather than Raman intensity itself.Multichannel detectors with outstanding sensitivity,rapid acquisition speed and low noise level have been widely equipped in Raman instruments for the measurement of Raman signal.In this mini-review,we first introduce the recent advances of Raman spectroscopy of 2DMs.Then we take the most commonly used CCD detector and IGA array detector as examples to overview the various noise sources in Raman measurements and analyze their potential influences on SNR of Raman signal in experiments.This overview can contribute to a better understanding on the SNR of Raman signal and the performance of multichannel detector for numerous researchers and instrumental design for industry,as well as offer practical strategies for improving spectral quality in routine measurement. 展开更多
关键词 multichannel detectors signal-to-noise ratio dark noise shot noise
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Calculation method of the signal-to-noise ratio attribute of seismic data based on structural orientation
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作者 Zhao Yan Mao Ning-Bo Chen Xu 《Applied Geophysics》 SCIE CSCD 2019年第4期455-462,560,共9页
At present,most signal-to-noise ratio(SNR)estimation methods can only calculate the global and not the local SNR of seismic data.This paper proposes a calculation method of a structure-oriented-based seismic SNR attri... At present,most signal-to-noise ratio(SNR)estimation methods can only calculate the global and not the local SNR of seismic data.This paper proposes a calculation method of a structure-oriented-based seismic SNR attribute.The purpose is to characterize the temporal and spatial variation of the seismic data SNR.First,the local slope parameters of the seismic events are calculated using a plane wave decomposition filter.Then,the singular value decomposition method is used to calculate the local seismic data SNR,thereby obtaining it in time and space.The proposed method overcomes the insufficiency of a conventional global SNR to characterize any local seismic data features and uses the SNR as an attribute of seismic data to more accurately describe the signal-noise energy distribution characteristics of seismic data in time and space.The results of a theoretical model test and real data processing show that the SNR attribute can be used not only for seismic data quality evaluation but also for analysis and evaluation of denoising methods. 展开更多
关键词 Seismic data signal-to-noise ratio attribute local slope singular value decomposition structure-oriented
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Signal-to-noise ratio comparison of angular signal radiography and phase stepping method
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作者 Wali Faiz 朱佩平 +4 位作者 胡仁芳 高昆 吴朝 鲍园 田扬超 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第12期173-178,共6页
Grating-based x-ray phase contrast imaging has the potential to be applied in future medical applications as it is compatible with both laboratory and synchrotron source. However, information retrieval methods are imp... Grating-based x-ray phase contrast imaging has the potential to be applied in future medical applications as it is compatible with both laboratory and synchrotron source. However, information retrieval methods are important because acquisition speed, scanning mode, image quality, and radiation dose depend on them. Phase-stepping (PS) is a widely used method to retrieve information, while angular signal radiography (ASR) is a newly established method. In this manuscript, signal-to-noise ratios (SNRs) of ASR are compared with that of PS. Numerical experiments are performed to validate theoretical results. SNRs comparison shows that for refraction and scattering images ASR has higher SNR than PS method, while for absorption image both methods have same SNR. Therefore, our conclusions would have guideline in future preclinical and clinical applications. 展开更多
关键词 angular signal radiography (ASR) phase-stepping (PS) signal-to-noise ratio (SNRs) information retrieval method
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Efficient Method to Extract Coupling Ratio and Round-trip Loss Parameters of Optical Waveguide Ring Resonator
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作者 HAN Xiu-you PANG Fu-fei +1 位作者 FANG Zu-jie ZHAO Ming-shan 《Semiconductor Photonics and Technology》 CAS 2008年第3期158-161,173,共5页
Based on the measurement of the contrast ratios of the transmission spectra from the throughput and drop ports of ring resonator, an efficient method is proposed to extract the coupling ratio and round-trip loss of th... Based on the measurement of the contrast ratios of the transmission spectra from the throughput and drop ports of ring resonator, an efficient method is proposed to extract the coupling ratio and round-trip loss of the integrated optical waveguide ring resonator. The parameters of a racetrack resonator prepared by ion-exchange technique in K9 optical glass substrate are examined, which demonstrates the validity of this method. The accuracy and applicable range of this method are also discussed. 展开更多
关键词 integrated optics waveguide ring resonator coupling ratio round-trip loss
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Local Correlated Noise Improvement of Signal-to-Noise Ratio Gain in an Ensemble of Noisy Neuron
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作者 Tianquan Feng Qingrong Chen Ming Yi 《Journal of Intelligent Learning Systems and Applications》 2018年第3期104-119,共16页
We theoretically investigate the collective response of an ensemble of leaky integrate-and-fire neuron units to a noisy periodic signal by including local spatially correlated noise. By using the linear response theor... We theoretically investigate the collective response of an ensemble of leaky integrate-and-fire neuron units to a noisy periodic signal by including local spatially correlated noise. By using the linear response theory, we obtained the analytic expression of signal-to-noise ratio (SNR). Numerical simulation results show that the rms amplitude of internal noise can be increased up to?an optimal value where the output SNR reaches a maximum value. Due to the existence of the local spatially correlated noise in the units of the ensemble, the SNR gain of the collective ensemble response can exceed unity and can be optimized when the nearest-neighborhood correlation is negative. This nonlinear collective phenomenon of SNR gain amplification in an ensemble of leaky integrate-and-fire neuron units can be related to the array stochastic resonance (SR) phenomenon. Furthermore, we also show that the SNR gain can also be optimized by tuning the number of neuron units, frequency and?amplitude of the weak periodic signal. The present study illustrates the potential to utilize the local spatially correlation noise and the number of ensemble units for optimizing the collective response of the neuron to inputs, as well as a guidance in the design of information processing devices to weak signal detection. 展开更多
关键词 Array Stochastic Resonance signal-to-noise ratio LOCAL Correlation NOISY NEURONS
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