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Moving mirror speed compound control of the Fourier transform spectrometer based on T-method 认领 引用
1
作者 HUANG Ying DUAN Juan +2 位作者 GUO Qian DING Lei HUA Jian-Wen 《红外与毫米波学报》 SCIE EI CAS CSCD 北大核心 2026年第1期137-147,共11页
The Fourier transform spectrometer(FTS)is a precision infrared detection instrument.It adopts Mi⁃chelson interference splitting,and the moving mirror is one of the core components.The uniformity and stability of the m... The Fourier transform spectrometer(FTS)is a precision infrared detection instrument.It adopts Mi⁃chelson interference splitting,and the moving mirror is one of the core components.The uniformity and stability of the moving mirror’s speed directly affect the quality of the subsequent interferogram,so it is necessary to carry out high-precision motion control of the moving mirror.For some FTS with moving mirror in low-speed motion,the traditional M-method can no longer meet the requirements of speed measurement accuracy.In addition,when the moving mirror moves at a low speed,the speed stability is more easily affected by external mechanical distur⁃bance.Based on the stability requirement of the low-speed moving mirror,this paper studies the motion control of the moving mirror based on the T-method measuring speed.It proposes a high-precision algorithm to obtain the measured and expected value of the velocity.By establishing the mathematical model and dynamic equation of the controlled object,the speed feedforward input is obtained,and then the compound speed controller based on the feedforward control is designed.The control algorithm is implemented by the FPGA hardware platform and ap⁃plied to the FTS.The experimental results show that the peak-to-peak velocity error is 0.0182,and the root mean square(RMS)velocity error is 0.0027.To test the anti-interference capability of the moving mirror speed control system,the sinusoidal excitation force of 5 mg,7.5 mg,and 10 mg is applied in the moving mirror motion direc⁃tion on the FTS platform.Under each given magnitude,the scanning of each frequency point in 2~200 Hz is car⁃ried out.The experimental results show that the peak-to-peak velocity error and the RMS velocity error are propor⁃tional to the excitation magnitude.Under the 5 mg excitation,the maximum peak-to-peak velocity error is 0.0724,and the maximum RMS velocity error is 0.0225.From a comprehensive analysis of spectrum stability and the sampling interval error of the infrared focal plane detector,the moving mirror velocity uniformity at 5 mg can meet both requirements.This enables the FTS to possess certain anti-interference capability even when ap⁃plied in micro-vibration environments.This design provides a technical means for realizing the speed control of the moving mirror with low speed and high stability.Also,it makes the FTS have wider applications. 展开更多
关键词 Fourier transform spectrometer speed control T-method speed feedforward velocity uniformity
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Distributed acoustic sensing data pattern recognition with a short-time Fourier transform downsampling module 认领 引用
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作者 Wenhao ZHU Yulong CAO 《Optoelectronics Letters》 EI 2026年第4期216-222,共7页
Distributed acoustic sensing(DAS)technology is widely used in seismic monitoring,intrusion detection,and other fields due to its advantages of wide monitoring range and low cost.However,the problems of complex signal ... Distributed acoustic sensing(DAS)technology is widely used in seismic monitoring,intrusion detection,and other fields due to its advantages of wide monitoring range and low cost.However,the problems of complex signal processing and large data volume limit its applications.This paper proposes a downsampling method based on short-time Fourier transform,which reduces the length of the time series while retaining high-frequency information.Experiments show that this method improves the efficiency and classification performance of the model,with an F1 value of 0.9147 on a four-class private dataset and an accuracy of 0.9944 on a two-class public dataset. 展开更多
关键词 data volume downsampling distributed acoustic sensing das technology signal processing short time fourier transform distributed acoustic sensing seismic monitoringintrusion detectionand downsampling method
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Multiple point cloud encryption based on principal component analysis and fractional Fourier transform 认领 引用
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作者 LI Xinze YU Lei +1 位作者 NIE Jiafa SUN Yan 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2026年第2期393-411,共19页
In view of the large amount of data and dense pixel points in point cloud files,this article proposes a multiple point cloud file encryption algorithm based on principal component analysis(PCA)and fractional Fourier t... In view of the large amount of data and dense pixel points in point cloud files,this article proposes a multiple point cloud file encryption algorithm based on principal component analysis(PCA)and fractional Fourier transform(FrFT).In this method,a point cloud data matrix(PCDM)is generated by extracting the coordinates and color information of the point cloud,then using PCA to reduce the dimension of a sequence of PCDMs,which are spliced and scrambled to produce a feature vector matrix and a dimension-reduced matrix(DRM)for encryption and reconstruction.Then using the hyperchaotic Lorenz system to generate the random phase masks and the orders of the FrFT.These two parameters will be used as keys to encrypt the point cloud feature vector matrix.The simulation results verify that the encryption algorithm can quickly encrypt multiple point cloud files,and the quality of the point cloud files obtained by decryption and reconstruction is good.The algorithm also has a large enough key space and highly sensitive keys,which means it has good security and strong robustness to different attacks. 展开更多
关键词 image encryption point cloud hyperchaotic system principal component analysis fractional Fourier Transform
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Pricing power option under NIG model using fast Fourier transform 认领 引用
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作者 LI Cui-xiang WANG Meng-na +1 位作者 LIU Hui-li LI Wen-han 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2025年第2期327-342,共16页
The aim of this paper is to price power option with its underlying asset price following exponential normal inverse gaussian(NIG)process.We first find the risk neutral equivalent martingale measure Q by Esscher transf... The aim of this paper is to price power option with its underlying asset price following exponential normal inverse gaussian(NIG)process.We first find the risk neutral equivalent martingale measure Q by Esscher transform.Then,using the Fourier transform and its inverse,we derive the analytical pricing formulas of power options which are expressed in the form of Fourier integral.In addition,the fast Fourier transform(FFT)algorithm is applied to calculate these pricing formulas.Finally,Shangzheng 50ETF options are chosen to test our results.Estimating the parameters in NIG process by maximum likelihood method,we show that the NIG prices are much closer to market prices than the Black-Scholes-Merton(BSM)ones. 展开更多
关键词 power option NIG process Esscher transform Fourier transform FFT algorithm
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Microstructure effect of mechanical and cracking behaviors on brittle rocks using image-based fast Fourier transform method 认领 引用
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作者 Mingyao Li Lei Peng +1 位作者 Dejun Liu Jianping Zuo 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2025年第1期399-413,共15页
The internal microstructures of rock materials, including mineral heterogeneity and intrinsic microdefects, exert a significant influence on their nonlinear mechanical and cracking behaviors. It is of great significan... The internal microstructures of rock materials, including mineral heterogeneity and intrinsic microdefects, exert a significant influence on their nonlinear mechanical and cracking behaviors. It is of great significance to accurately characterize the actual microstructures and their influence on stress and damage evolution inside the rocks. In this study, an image-based fast Fourier transform (FFT) method is developed for reconstructing the actual rock microstructures by combining it with the digital image processing (DIP) technique. A series of experimental investigations were conducted to acquire information regarding the actual microstructure and the mechanical properties. Based on these experimental evidences, the processed microstructure information, in conjunction with the proposed micromechanical model, is incorporated into the numerical calculation. The proposed image-based FFT method was firstly validated through uniaxial compression tests. Subsequently, it was employed to predict and analyze the influence of microstructure on macroscopic mechanical behaviors, local stress distribution and the internal crack evolution process in brittle rocks. The distribution of feldspar is considerably more heterogeneous and scattered than that of quartz, which results in a greater propensity for the formation of cracks in feldspar. It is observed that initial cracks and new cracks, including intragranular and boundary ones, ultimately coalesce and connect as the primary through cracks, which are predominantly distributed along the boundary of the feldspar. This phenomenon is also predicted by the proposed numerical method. The results indicate that the proposed numerical method provides an effective approach for analyzing, understanding and predicting the nonlinear mechanical and cracking behaviors of brittle rocks by taking into account the actual microstructure characteristics. 展开更多
关键词 Rock microstructure Cracking process Brittle rocks Fast Fourier transform(FFT) Digital image processing(DIP)
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Reduced Basis Method Based on Fourier Transform for Time-Dependent Parameterized Nonlocal Problems 认领 引用 被引量：1
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作者 Dou Dai Huailing Song Yuming Ba 《Communications in Mathematical Research》 CSCD 2025年第1期69-102,共34页
In the paper,a reduced basis(RB)method for time-dependent nonlocal problems with a special parameterized fractional Laplace kernel function is proposed.Because of the lack of sparsity of discretized nonlocal systems c... In the paper,a reduced basis(RB)method for time-dependent nonlocal problems with a special parameterized fractional Laplace kernel function is proposed.Because of the lack of sparsity of discretized nonlocal systems compared to corresponding local partial differential equation(PDE)systems,model reduction for nonlocal systems becomes more critical.The method of snapshots and greedy(MOS-greedy)algorithm of RB method is developed for nonlocal problems with random inputs,which provides an efficient and reliable approximation of the solution.A major challenge lies in the excessive influence of the time domain on the model reduction process.To address this,the Fourier transform is applied to convert the original time-dependent parabolic equation into a frequency-dependent elliptic equation,where variable frequencies are independent.This enables parallel computation for approximating the solution in the frequency domain.Finally,the proposed MOS-greedy algorithm is applied to the nonlocal diffusion problems.Numerical results demonstrate that it provides an accurate approximation of the full order problems and significantly improves computational efficiency. 展开更多
关键词 Nonlocal problems reduced basis method method of snapshots greedy algorithm Fourier transform
Cytoprotective activity of Pogonatherum paniceum(Lam.)Hack.ethanolic extract evaluated by synchrotron radiation-based Fourier transform infrared microspectroscopy 认领 引用
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作者 Benjawan Dunkhunthod Kanjana Thumanu +2 位作者 Yothin Teethaisong Priyada Sittisart Patcharawan Sittisart 《Journal of Integrative Medicine》 SCIE CAS CSCD 2025年第2期182-194,共13页
Objective:The present study investigated the cytoprotective effects of a Pogonatherum paniceum extract prepared with 80%ethanol(PPE)using synchrotron radiation-based Fourier transform infrared(SR-FTIR)microspectroscop... Objective:The present study investigated the cytoprotective effects of a Pogonatherum paniceum extract prepared with 80%ethanol(PPE)using synchrotron radiation-based Fourier transform infrared(SR-FTIR)microspectroscopy and determined its phytochemical profile.Methods:The volatile and polyphenolic compounds in PPE were characterized using gas chromatography–mass spectrometry and liquid chromatography–mass spectrometry,respectively.The antioxidant capacity of PPE was evaluated using chemical and cell-based assays.The SR-FTIR microspectroscopy was performed to evaluate the cytoprotective effect of PPE by identifying changes in macromolecule composition in tert-butyl hydroperoxide(t BuOOH)-induced oxidative damage in RAW264.7 cells.Results:A total of 48 volatile compounds and 28 polyphenol components were found in PPE.PPE exhibited a high potential for antioxidant activity by scavenging the intracellular reactive oxygen species in t Bu OOH-induced oxidative damage in RAW264.7 cells.PPE treatment also significantly protected RAW264.7 cells against t BuOOH-induced toxicity and restored cell viability.The SR-FTIR analysis revealed that t BuOOH increased the lipid and ester lipid content in RAW264.7 cells.The PPE exerted a cytoprotective effect by decreasing the levels of lipid and ester lipid compounds that had been elevated by t BuOOH in RAW264.7 cells.These findings indicate that PPE has cytoprotective potential due to its ability to inhibit endogenous reactive oxygen species.Conclusion:This study extends the current knowledge on the phytochemistry of PPE and its antioxidant and cytoprotective effects.These findings support the use of SR-FTIR microspectroscopy to determine the cytoprotective effects of natural products.PPE extract may be a candidate compound for new therapeutics and nutraceuticals that target the prevention of oxidative stress-associated diseases. 展开更多
关键词 Pogonatherum paniceum Reactive oxygen species Antioxidant Phytochemical Cytoprotective Synchrotron radiation-based Fourier transform infrared microspectroscopy
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Multi-Scale Fusion Network Using Time-Division Fourier Transform for Rolling Bearing Fault Diagnosis 认领 引用
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作者 Ronghua Wang Shibao Sun +3 位作者 Pengcheng Zhao Xianglan Yang Xingjia Wei Changyang Hu 《Computers, Materials & Continua》 SCIE EI 2025年第8期3519-3539,共21页
The capacity to diagnose faults in rolling bearings is of significant practical importance to ensure the normal operation of the equipment.Frequency-domain features can effectively enhance the identification of fault ... The capacity to diagnose faults in rolling bearings is of significant practical importance to ensure the normal operation of the equipment.Frequency-domain features can effectively enhance the identification of fault modes.However,existing methods often suffer from insufficient frequency-domain representation in practical applications,which greatly affects diagnostic performance.Therefore,this paper proposes a rolling bearing fault diagnosismethod based on aMulti-Scale FusionNetwork(MSFN)using the Time-Division Fourier Transform(TDFT).The method constructs multi-scale channels to extract time-domain and frequency-domain features of the signal in parallel.A multi-level,multi-scale filter-based approach is designed to extract frequency-domain features in a segmented manner.A cross-attention mechanism is introduced to facilitate the fusion of the extracted time-frequency domain features.The performance of the proposed method is validated using the CWRU and Ottawa datasets.The results show that the average accuracy of MSFN under complex noisy signals is 97.75%and 94.41%.The average accuracy under variable load conditions is 98.68%.This demonstrates its significant application potential compared to existing methods. 展开更多
关键词 Rolling bearing fault diagnosis time-division fourier transform cross-attention multi-scale feature fusion
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Quantum entangled fractional Fourier transform based on the IWOP technique 认领 引用 被引量：3
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作者 张科 李兰兰 +3 位作者 余盼盼 周莹 郭大伟 范洪义 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第4期165-170,共6页
In our previous papers,the classical fractional Fourier transform theory was incorporated into the quantum theoretical system using the theoretical method of quantum optics,and the calculation produced quantum mechani... In our previous papers,the classical fractional Fourier transform theory was incorporated into the quantum theoretical system using the theoretical method of quantum optics,and the calculation produced quantum mechanical operators corresponding to the generation of fractional Fourier transform.The core function of the coordinate-momentum exchange operators in the addition law of fractional Fourier transform was analyzed too.In this paper,the bivariate operator Hermite polynomial theory and the technique of integration within an ordered product of operators(IWOP)are used to establish the entanglement fractional Fourier transform theory to the extent of quantum.A new function generating formula and an operator for generating quantum entangled fractional Fourier transform are obtained using the fractional Fourier transform relationship in a pair of conjugated entangled state representations. 展开更多
关键词 fractional Fourier transform coordinate-momentum exchange operators bivariate operator Hermite polynomial theory the technique of integration within an ordered product of operators quantum entangled fractional Fourier transform
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Realization of quantum Fourier transform over Z_N 认领 引用 被引量：3
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作者 付向群 鲍皖苏 +1 位作者 李发达 张宇超 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第2期93-98,共6页
Since the difficulty in preparing the equal superposition state of amplitude is 1/√N, we construct a quantile transform of quantum Fourier transform （QFT） over ZN based on the elementary transforms, such as Hadamar... Since the difficulty in preparing the equal superposition state of amplitude is 1/√N, we construct a quantile transform of quantum Fourier transform （QFT） over ZN based on the elementary transforms, such as Hadamard transform and Pauli transform. The QFT over Z_N can then be realized by the quantile transform, and used to further design its quantum circuit and analyze the requirements for the quantum register and quantum gates. However, the transform needs considerable quantum computational resources and it is difficult to construct a high-dimensional quantum register. Hence, we investigate the design of t-bit quantile transform, and introduce the definition of t-bit semiclassical QFT over Z_N. According to probability amplitude, we prove that the transform can be used to realize QFT over ZN and further design its quantum circuit. For this transform, the requirements for the quantum register, the one-qubit gate, and two-qubit gate reduce obviously when compared with those for the QFT over Z_N. 展开更多
关键词 quantum Fourier transform semiclassical quantum Fourier transform quantum algorithm
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Application of short-time Fourier transform to high-rise frame structural-health monitoring based on change of inherent frequency over time 认领 引用
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作者 郭少霞 PEI Qiang 《Journal of Chongqing University》 2017年第1期1-10,共10页
The high-rise frame structure has become more and more widespread, like its damage from the complication of the environment. The traditional method of damage detection, which is only suitable for the stationary signal... The high-rise frame structure has become more and more widespread, like its damage from the complication of the environment. The traditional method of damage detection, which is only suitable for the stationary signal, does not apply to a high-rise frame structure because its damage signal is non-stationary. Thus, this paper presents an application of the short-time Fourier transform(STFT) to damage detection of high-rise frame structures. Compared with the fast Fourier transform, STFT is found to be able to express the frequency spectrum property of the time interval using the signal within this interval. Application of STFT to analyzing a Matlab model and the shaking table test with a twelve-story frame-structure model reveals that there is a positive correlation between the slope of the frequency versus time and the damage level. If the slope is equal to or greater than zero, the structure is not damaged. If the slope is smaller than zero, the structure is damaged, and the less the slope is, the more serious the damage is. The damage results from calculation based on the Matlab model are consistent with those from the shaking table test, demonstrating that STFT can be a reliable tool for the damage detection of high-rise frame structures. 展开更多
关键词 short-time Fourier transform fast Fourier transform damage identification shaking table test time-frequency analysis
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Supercritical water syntheses of transition metal-doped CeO_2 nano-catalysts for selective catalytic reduction of NO by CO:An in situ diffuse reflectance Fourier transform infrared spectroscopy study 认领 引用 被引量：17
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作者 Xiaoxia Dai Weiyu Jiang +4 位作者 Wanglong Wang Xiaole Weng Yuan Shang Yehui Xue Zhongbiao Wu 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2018年第4期728-735,共8页
In the present study,we synthesized CeO2 catalysts doped with various transition metals(M=Co,Fe,or Cu)using a supercritical water hydrothermal route,which led to the incorporation of the metal ions in the CeO2 lattice... In the present study,we synthesized CeO2 catalysts doped with various transition metals(M=Co,Fe,or Cu)using a supercritical water hydrothermal route,which led to the incorporation of the metal ions in the CeO2 lattice,forming solid solutions.The catalysts were then used for the selective catalytic reduction(SCR)of NO by CO.The Cu‐doped catalyst exhibited the highest SCR activity;it had a T50(i.e.,50%NO conversion)of only 83°C and a T90(i.e.,90%NO conversion)of 126°C.Such an activity was also higher than in many state‐of‐the‐art catalysts.In situ diffuse reflectance Fourier transform infrared spectroscopy suggested that the MOx‐CeO2 catalysts(M=Co and Fe)mainly followed an Eley‐Rideal reaction mechanism for CO‐SCR.In contrast,a Langmuir‐Hinshelwood SCR reaction mechanism occurred in CuO‐CeO2 owing to the presence of Cu+species,which ensured effective adsorption of CO.This explains why CuO‐CeO2 exhibited the highest activity with regard to the SCR of NO by CO. 展开更多
关键词 Supercritical water Nitrogen oxides CO Selective catalytic reduction Diffuse reflectance Fourier transform infrared spectroscopy CeO2
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Mechanism Study of Rice Straw Pyrolysis by Fourier Transform Infrared Technique 认领 引用 被引量：12
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作者 付鹏 胡松 +4 位作者 向军 孙路石 杨涛 张安超 张军营 《Chinese Journal of Chemical Engineering》 SCIE EI CAS 2009年第3期522-529,共8页
The pyrolysis mechanism of rice straw (RS) was investigated using a tube reactor with Fourier trans-form infrared (FTIR) spectroscopy and thermogravimetric analyzer. The results show that the maximum pyrolysis rate in... The pyrolysis mechanism of rice straw (RS) was investigated using a tube reactor with Fourier trans-form infrared (FTIR) spectroscopy and thermogravimetric analyzer. The results show that the maximum pyrolysis rate increases with increasing heating rate and the corresponding temperature also increases. The three-pseudocomponent model could describe the pyrolysis behavior of rice straw accurately. The main pyrolysis gas products are H2O, CO2, CO, CH4, HCHO (formaldehyde), HCOOH (formic acid), CH3OH (methanol), C6H5OH (phenol), etc. The releasing of H2O, CO2, CO and CH4 mainly focuses at 220-400°C. The H2O formation process is separated into two stages corresponding to the evaporation of free water and the formation of primary volatiles. The release of CO2 first increases with increasing temperature and gets the maximum at 309°C. The releasing behavior of CO is similar to H2O and CO2 between 200 and 400°C. The production of CH4 happens, compared to CO2 and CO, at higher temperatures of 275-400°C with the maximum at 309°C. When the temperature exceeds 200°C, hy-droxyl and aliphatic C H groups decrease significantly, while C O, olefinic C C bonds and ether structures in-crease first in the chars and then the aromatic structure develops with rising temperature. Above 500°C, the material becomes increasingly more aromatic and the ether groups decreases with an increase of temperature. The aromati-zation process starts at ≈350°C and continues to higher temperatures. 展开更多
关键词 rice straw pyrolysis mechanism Fourier transform intrared
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Chirp-Rate Resolution of Fractional Fourier Transform in Multi-component LFM Signal 认领 引用 被引量：13
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作者 刘锋 黄宇 +1 位作者 陶然 王越 《Journal of Beijing Institute of Technology》 EI CAS 2009年第1期74-78,共5页
Distinguishing close chirp-rates of different linear frequency modulation （LFM） signals under concentrated and complicated signal environment was studied. Firstly, detection and parameter estimation of multi-compone... Distinguishing close chirp-rates of different linear frequency modulation （LFM） signals under concentrated and complicated signal environment was studied. Firstly, detection and parameter estimation of multi-component LFM signal were used by discrete fast fractional Fourier transform （FrFT）. Then the expression of chirp-rate resolution in fractional Fourier domain （FrFD） was deduced from discrete normalize time-frequency distribution, when multi-component LFM signal had only one center frequency. Furthermore, the detail influence of the sampling time, sampling frequency and chirp-rate upon the resolution was analyzed by partial differential equation. Simulation results and analysis indicate that increasing the sampling time can enhance the resolution, but the influence of the sampling frequency can he omitted. What＇s more, in multi-component LFM signal, the chirp-rate resolution of FrFT is no less than a minimal value, and it mainly dependent on the biggest value of chirp-rates, with which it has an approximately positive exponential relationship. 展开更多
关键词 fractional Fourier transform（FrFT） resolution linear frequency modulation（LFM） signal chirp-rate
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Retrieval algorithm of quantitative analysis of passive Fourier transform infrared (FTRD) remote sensing measurements of chemical gas cloud from measuring the transmissivity by passive remote Fourier transform infrared 认领 引用 被引量：13
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作者 刘志明 刘文清 +4 位作者 高闽光 童晶晶 张天舒 徐亮 魏秀丽 《Chinese Physics B》 SCIE EI CAS 2008年第11期4184-4192,共9页
Passive Fourier transform infrared （FTIR） remote sensing measurement of chemical gas cloud is a vital technology. It takes an important part in many fields for the detection of released gases. The principle of conce... Passive Fourier transform infrared （FTIR） remote sensing measurement of chemical gas cloud is a vital technology. It takes an important part in many fields for the detection of released gases. The principle of concentration measurement is based on the Beer-Lambert law. Unlike the active measurement, for the passive remote sensing, in most cases, the difference between the temperature of the gas cloud and the brightness temperature of the background is usually a few kelvins. The gas cloud emission is almost equal to the background emission, thereby the emission of the gas cloud cannot be ignored. The concentration retrieval algorithm is quite different from the active measurement. In this paper, the concentration retrieval algorithm for the passive FTIR remote measurement of gas cloud is presented in detail, which involves radiative transfer model, radiometric calibration, absorption coefficient calculation, et al. The background spectrum has a broad feature, which is a slowly varying function of frequency. In this paper, the background spectrum is fitted with a polynomial by using the Levenberg-Marquardt method which is a kind of nonlinear least squares fitting algorithm. No background spectra are required. Thus, this method allows mobile, real-time and fast measurements of gas clouds. 展开更多
关键词 passive remote measurement Fourier transform infrared （FTIR） gas cloud sensing concentration retrieval
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Wavelet-fractional Fourier transforms 认领 引用 被引量：6
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作者 袁琳 《Chinese Physics B》 SCIE EI CAS 2008年第1期170-179,共10页
This paper extends the definition of fractional Fourier transform （FRFT） proposed by Namias V by using other orthonormal bases for L^2（R） instead of Hermite-Gaussian functions. The new orthonormal basis is gained ... This paper extends the definition of fractional Fourier transform （FRFT） proposed by Namias V by using other orthonormal bases for L^2（R） instead of Hermite-Gaussian functions. The new orthonormal basis is gained indirectly from multiresolution analysis and orthonormal wavelets. The so defined FRFT is called wavelets-fractional Fourier transform. 展开更多
关键词 multiresolution analysis fractional Fourier transform wavelets-fractional Fourier transform
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Reservoir information extraction using a fractional Fourier transform and a smooth pseudo Wigner-Ville distribution 认领 引用 被引量：6
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作者 王祝文 王晓丽 +3 位作者 向旻 刘菁华 张雪昂 杨闯 《Applied Geophysics》 SCIE CSCD 2012年第4期391-400,494,495,共10页
Currently, it is difficult for people to express signal information simultaneously in the time and frequency domains when analyzing acoustic logging signals using a simple-time or frequency-domain method. It is diffic... Currently, it is difficult for people to express signal information simultaneously in the time and frequency domains when analyzing acoustic logging signals using a simple-time or frequency-domain method. It is difficult to use a single type of time-frequency analysis method, which affects the feasibility of acoustic logging signal analysis. In order to solve these problems, in this paper, a fractional Fourier transform and smooth pseudo Wigner Ville distribution （SPWD） were combined and used to analyze array acoustic logging signals. The time-frequency distribution of signals with the variation of orders of fractional Fourier transform was obtained, and the characteristics of the time-frequency distribution of different reservoirs under different orders were summarized. Because of the rotational characteristics of the fractional Fourier transform, the rotation speed of the cross terms was faster than those of primary waves, shear waves, Stoneley waves, and pseudo Rayleigh waves. By choosing different orders for different reservoirs according to the actual circumstances, the cross terms were separated from the four kinds of waves. In this manner, we could extract reservoir information by studying the characteristics of partial waves. Actual logging data showed that the method outlined in this paper greatly weakened cross-term interference and enhanced the ability to identify partial wave signals. 展开更多
关键词 Fractional Fourier transform smooth pseudo Wigner-Ville distribution arrayacoustic logging signal processing reservoirs
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Joint Wavelet-Fractional Fourier Transform 认领 引用 被引量：3
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作者 宋军 何锐 +2 位作者 袁好 周军 范洪义 《Chinese Physics Letters》 SCIE EI CAS CSCD 2016年第11期18-21,共4页
Based on Dirac＇s representation theory and the technique of integration within an ordered product of operators, we put forward the joint wavelet-fractional Fourier transform in the context of quantum mechanics. Its c... Based on Dirac＇s representation theory and the technique of integration within an ordered product of operators, we put forward the joint wavelet-fractional Fourier transform in the context of quantum mechanics. Its corresponding transformation operator is found and the normally ordered form is deduced. This kind of transformation may be applied to analyzing and identifying quantum states. 展开更多
关键词 of or on is in Joint Wavelet-Fractional Fourier Transform
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The role of fluid polarity in the swelling of sodium-montmorillonite clay:A molecular dynamics and Fourier transform infrared spectroscopy study 认领 引用 被引量：5
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作者 Dinesh R.Katti Keshab B.Thapa Kalpana S.Katti 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2018年第6期1133-1144,共12页
Swelling clays are found extensively in various parts of the world, and sodium-montmorillonite(NaMMT) is the main constituent of an expansive clay mineral. In this work, the swelling behavior of NaMMT clay with a wide... Swelling clays are found extensively in various parts of the world, and sodium-montmorillonite(NaMMT) is the main constituent of an expansive clay mineral. In this work, the swelling behavior of NaMMT clay with a wide range of organic fluids, high polar through low polar fluids, is studied using a combination of Fourier transform infrared(FTIR) technique and molecular dynamics(MD) simulations.The construction of the representative clayefluid models is carried out, and the nature of nonbonded interactions between clay and fluids is studied using MD. Our FTIR and MD simulations results suggest the significant nonbonded interactions between Na-MMT clay and polar fluids, such as formamide and water. The nonbonded interactions of Na-MMT with methanol and acetone are significantly less than those in Na-MMT with polar fluids. The interactions of the fluids with various entities of the clay such as Sie O, Fee OH, Mge OH, and Ale OH captured via the spectroscopy experiments and modeling provide a finer understanding of the interactions and their contributions to swelling. The MD simulations are able to capture the band shifts observed in the spectra obtained in the spectroscopy experiments. This work also captures the conformations of interlayer sodium ions with formamide, water, methanol, and acetone during swelling. These nonbonded interactions provide insight into the molecular mechanism that the polarity of fluids plays an important role in the initiation of interlayer swelling, alteration in the orientations, and evolution of microstructure of swelling clays at the molecular scale. 展开更多
关键词 Swelling clays Montmorillonite Fourier transform infrared(FTIR) technique Molecular dynamics(MD) Organic fluids Polarity
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INTERFERENCE MITIGATING BASED ON FRACTIONAL FOURIER TRANSFORM IN TRANSFORM DOMAIN COMMUNICATION SYSTEM 认领 引用 被引量：6
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作者 Wang Chuandan Zhang Zhongpei Li Shaoqian 《Journal of Electronics(China)》 2007年第2期181-186,共6页
The method of FRactional Fourier Transform (FRFT) is introduced to Transform Domain Communication System (TDCS) for signal transforming in the paper after theoretical analysis. The method yields optimal Basis Function... The method of FRactional Fourier Transform (FRFT) is introduced to Transform Domain Communication System (TDCS) for signal transforming in the paper after theoretical analysis. The method yields optimal Basis Function (BF) by FRFT with optimal transform angle. The TDCS using the proposed method has wider usable spectrum, stronger robustness and better ability of anti non-stationary jamming than using usual methods, such as Fourier Transform (FT), Auto Regressive (AR), Wavelet Transform (WT), etc. The main simulation results are as follows. First, the Bit Error Rate (BER) Pb is close to theoretical bound of no jamming no matter in single tone or in linear chirp interference. Second, the interference-to-signal ratio J /E is at least 12dB more than that of Direct Spread Spectrum System (DSSS) under the same BER if the spectrum hopping-to-signal ratio is 1:20 in chirp plus hopping interfering. Third, the Eb /N 0(when estimation difference is 90% between trans- mitter and receiver) is about 3.5dB or about 0.5dB (when estimation difference is 10% between transmitter and receiver) more than that of theoretical result when no estimation difference un-der Pb=10-2. 展开更多
关键词 Transform Domain Communication System （TDCS） Basis Function （BF） Fourier Transform （FT） FRactional Fourier Transform （FRFT） Hopping jamming
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