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Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A spectral transform maps a function from one domain into an appropriate function in another domain where certain characteristics of the function are clearly visible. Spectral transforms have great importance in signal analysis, image processing, logic design, etc. The main problem with spectral transforms is their exponential computational complexity. In the case of discrete functions, spectral transform computation comes down to multiplying the transform matrix and the truth vector of the function. Most of the previously developed algorithms for spectral transforms computation are based on the fast Fourier transform algorithm, some use a compact representation of the functions (such as decision diagrams), and some use special single instruction multiple data hardware structures (such as graphics processing units). In the last years, a special type of graphics processing units with Tensor Cores has been developed for matrix multiplication. These units usually support matrix operations on limited data types and matrix dimensions. In this paper, we propose algorithms for 4-valued Reed–Muller–Fourier and Vilenkin–Chrestenson transforms on the Tensor Cores hardware. Our solution is a customization of the Cooley–Tuckey algorithm for execution on the hardware with specified limitations. Computation times of spectral transforms by the proposed algorithm are compared with computation times of the same transforms on a central processing unit by using serial and parallel algorithms, and on a standard graphics processing units. The described experiments showed that, for a large number of variables, both implementations that are executed on graphics processing units are significantly more efficient than those that are executed on central processing unit. If only implementations on graphics processing units are compared, for the functions of 14 variables, the Tensor Cores implementation of the Reed–Muller–Fourier transform is 2.03 times faster, and the implementation of the Vilenkin–Chrestenson transform is 1.5 times faster. Poorer results obtained for the Vilenkin–Chrestenson transform are due to the limited set of data types provided by the NVIDIA Turing Graphics Processing Units that were used in the experiments. Therefore, one integer spectral coefficient is represented by 4-byte values. Regardless, the proposed algorithms and the Tensor Cores architecture have proven to be a good solution for the spectral transforms calculations. [ABSTRACT FROM AUTHOR]

In this paper, we price a compound option with log asset price following an extended variance gamma process. The extended variance gamma process can control the skewness and kurtosis. The parameters of the model are estimated via the maximum likelihood method from historical data. We start with finding the risk neutral Esscher measure under which the discounted asset price process is a martingale. Then we derive an analytical pricing formula for compound option in terms of the Fourier integral of the characteristic function of extended variance gamma process, and we use this formula, in combination with the FFT algorithm, to calculate the compound option price across the whole spectrum of the exercise price. Finally, we present some numerical results for illustration. [ABSTRACT FROM AUTHOR]

The Fast Fourier Transform (FFT) is the basic building block for DSP applications where high processing speed is the critical requirement. Resource utilization and the number of computational stages in Radix-2 FFT structure implementation can be minimized by improving the performance of utilized multiplier and adder blocks. This work proposes a hardware design of an efficient Radix-2 FFT architecture using optimized multiplier and novel Parallel prefix (PP) adder. The designed FFT architecture results in low power and area with an increase in operation speed in comparison to the existing architectures. Our proposed Radix 2 FFT implementation results in 18.218 ns (6.030 ns logic delay and 12.118 ns router delay) in comparison with 24.003 ns delay for Wallace multiplier using Kogge Stone PP adder (M1P1), 24.162 ns delay for Wallace multiplier using Brent Kung PP adder (M2P2), 24.889 ns delay for Wallace multiplier using Landner Fischer PP adder (M3P3) and 22.827 ns delay for Wallace multiplier using Han Carlson PP adder (M4P4) algorithm. The proposed adder and hence the FFT processor can be used in different applications where high speed, low power, and less area is required. The novel PP architecture results in a 20.19% improvement in comparison with other state-of-art techniques. [ABSTRACT FROM AUTHOR]

Refined modelling of turbulence in two-spatial dimensions is necessary for reliability assessment of large-size structures such as wind turbines. Stochastic wave-based spectral representation (SWSR) method is a widely-used tool. However, the correlation of turbulent components is usually neglected in it. Based on the SWSR, a multi-dimension (n- D) multi-variable (n -V) continuous temporal-spatial field model is thus proposed in this study. The low efficiency exist in this model, which are also unavoidable in others when simulating turbulence in multi-spatial dimensions. One reason is the large number of sample functions in the Monte Carlo (MC)-based method. The other is the n -D matrix-based Fast Fourier Transform (FFT) algorithm in single sample generation. Therefore, an efficient method is given to improve efficiency in both two aspects. The former improvement is realized through defining multi-index dimension reduction (DR) expressions in the proposed model. The latter is based on the 1-D vector-based FFT algorithm, the key to which are the decoupling of n -D matrices and factorization of multi-index DR expressions. A numerical simulation of a stochastic wind field in two-spatial dimensions is designed to demonstrate the validity of the proposed method. Results show its improvement of efficiency in both views of sample sets and single sample generation. • A method is proposed for simulating turbulent wind fields in two-spatial dimensions. • The correlation between turbulent components is considered in this method. • The efficiency is improved in both view of sample sets and single sample generation. • It can combine with the PDEM for assessing wind-resistant reliability of structures. [ABSTRACT FROM AUTHOR]

The cycle frequencies of a cyclostationary signal can be used for the signal identification and classification, separation of the overlapped signals in cycle domain, and so on. Efficient cycle frequency acquisition depends on the fast measurement of cyclic autocorrelation function (CAF) or spectral correlation function (SCF) of the signal. Presently the relative efficient CAF and SCF measuring methods mainly include the cyclic correlogram, the well-known fast Fourier transform accumulation method (FAM), and so on. Motivated by these methods, a new efficient cycle frequency acquisition method which integrates the fast Fourier transform (FFT) algorithm with the autocorrelated cyclic autocorrelation function, named FACA, is presented. With the presented method, we can acquire the cycle frequencies of a cyclostationary signal more efficiently with a given level of reliability. Meanwhile, by enlarging the FFT window width of the FACA method we can get the same cycle frequency resolution as the benchmarked method FAM, but the computation cost still can be spared at this case.

With the development of High Voltage Direct Current (HVDC) and ultra HVDC, a growing number of high voltage film filter capacitors have been installed for harmonic suppression. But the capacitors generate severe audible noise in the converters, which has become more and more serious. Then it is important to imitate the practical working situation of capacitors for the research of noise characteristics to improve the capacitive performance in lab. In this paper, a FFT-based harmonic current control method is proposed for audible noise analysis of AC filter capacitor. Firstly, mathematical model of the Harmonic Current Injection System (HCIS) is built based on MATLAB. Then a Fast Fourier Transform (FFT) harmonics detection method is analyzed and used to detect the amplitude and phase of each harmonic considering a number of harmonic currents flowing through AC filter capacitors. Since the amplitude and phase spectrum of capacitor current are obtained, the Proportional Integral (PI) regulator is applied to adjust the specified harmonic amplitude to achieve zero-error control. Then accurate harmonic current can be injected to the tested capacitor and it will help to acquire the noise characteristics of the tested plant. At last, the simulation and experimental results validate the proposed strategy. [ABSTRACT FROM AUTHOR]

The fast Fourier transform (FFT) algorithm with window interpolation is the most commonly used and most effective method in harmonic analysis. However, the fast Fourier transform has a great dependence on the quality of the signal, and the existence of noise makes the detection result error. A harmonic detection method based on wavelet threshold preprocessing noise elimination and windowed interpolation FFT algorithm is proposed in this thesis. Firstly, de-noising the selected signals, and the wavelet coefficients are used to select the wavelet threshold to eliminate the noise in the signal. Then the signal after the de-noising is analysed by the Nuttall window interpolate FFT algorithm, and the calculation formula is derived by using the amplitude information content of four spectral lines. The simulation results show that the proposed method is more accurate and effective to detect the signal after de-noising.

THz Atmospheric Limb Sounder (TALIS) is a microwave radiometer designed by the National Space Science Center of the Chinese Academy of Sciences (NSSC, CAS) for measuring the vertical distribution of temperature and chemical constituents in the middle and upper atmosphere. The digital spectrometer is an important part of TALIS’ back end, which mainly realizes the function of spectral analysis. The radix 16 real-time complex fast Fourier transform (FFT) algorithm used in the digital spectrometer was obtained by improving and combining the parallel processing and complex processing of the FFT algorithm. In this study, the digital spectrometer parameter selection is systematically presented, and the effect of the digital spectrometer FFT algorithm on the TALIS system sensitivity is analyzed based on the TALIS system simulation model we established in the previous stage of this research. The results show that the actual full-band sensitivity obtained after using the FFT algorithm is consistent with the ideal full-band sensitivity of TALIS for different integration time, spectral resolutions, and quantization bits. However, the results of the comparison of the actual sub-band sensitivity after using the FFT algorithm with the ideal sub-band sensitivity show that the deterioration of the sub-band sensitivity will be caused by the FFT algorithm. The mean value of the deterioration ratio was found to be approximately 18%, and the maximum value of the deterioration ratio was approximately 33%.

In order to reduce the development cost of LED lattice display and the software design and debugging cycle. Proteus circuit simulation software is used to design LED dot matrix screen and its driving circuit, and CCS code debugging function is used to write the code. Aiming at the innovative practice activities of college students, the MSP430 and FFT are adopted to realize the acquisition of music signal and the display of music spectrum. Combined with directly designing hardware and welding debugging, the algorithm can be directly verified in this simulation design system environment, it can avoid the problem of hardware design scheme error and debugging, and greatly shorten the design time . At the same time, the design of circuit modification is more flexible, and on this basis, a variety of lattice spectrum can be extended. [ABSTRACT FROM AUTHOR]

The cycle frequencies of a cyclostationary signal can be used for the signal identification and classification, separation of the overlapped signals in cycle domain, and so on. Efficient cycle frequency acquisition depends on the fast measurement of cyclic autocorrelation function (CAF) or spectral correlation function (SCF) of the signal. Presently the relative efficient CAF and SCF measuring methods mainly include the cyclic correlogram, the well-known fast Fourier transform accumulation method (FAM), and so on. Motivated by these methods, a new efficient cycle frequency acquisition method which integrates the fast Fourier transform (FFT) algorithm with the autocorrelated cyclic autocorrelation function, named FACA, is presented. With the presented method, we can acquire the cycle frequencies of a cyclostationary signal more efficiently with a given level of reliability. Meanwhile, by enlarging the FFT window width of the FACA method we can get the same cycle frequency resolution as the benchmarked method FAM, but the computation cost still can be spared at this case. [ABSTRACT FROM AUTHOR]

The fast Fourier transform (FFT) algorithm with window interpolation is the most commonly used and most effective method in harmonic analysis. However, the fast Fourier transform has a great dependence on the quality of the signal, and the existence of noise makes the detection result error. A harmonic detection method based on wavelet threshold preprocessing noise elimination and windowed interpolation FFT algorithm is proposed in this thesis. Firstly, de-noising the selected signals, and the wavelet coefficients are used to select the wavelet threshold to eliminate the noise in the signal. Then the signal after the de-noising is analysed by the Nuttall window interpolate FFT algorithm, and the calculation formula is derived by using the amplitude information content of four spectral lines. The simulation results show that the proposed method is more accurate and effective to detect the signal after de-noising. [ABSTRACT FROM AUTHOR]

Summary: The problem of the dynamic responses of a semi‐infinite unsaturated poroelastic medium subjected to a moving rectangular load is investigated analytical/numerically. The dynamic governing equations are obtained with consideration of the compressibility of solid grain and pore fluid, inertial coupling, and viscous drag as well as capillary pressure in the unsaturated soil, and they can be easily degraded to the complete Biot's theory. Using the Fourier transform, the general solution for the equations is derived in the transformed domain, and then a corresponding boundary value problem is formulated. By introducing fast Fourier transform algorithm, the unsaturated soil vertical displacements, effective stresses, and pore pressures induced by moving load are computed, and some of the calculated results are compared with those for the degenerated solution of saturated soils and confirmed. The influences of the saturation, the load speed, and excitation frequency on the response of the unsaturated half‐space soil are investigated. The numerical results reveal that the effects of these parameters on the dynamic response of the unsaturated soil are significant. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Textile & Apparel / Tekstil ve Konfeksiyon is the property of Tekstil ve Konfeksiyon and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A new Tikhonov regularization method of Fuhry and Reichel [A new Tikhonov regularization method, Numerical Algorithms, 59:433-445, 2011] exhibits the excellent properties for ill-posed problems, but it can only deal with small or moderate size problems because of the expensive computation of singular value decomposition (SVD). In this paper, we extend the above new Tikhonov regularization method to solve large-scale problems, e.g., image restoration problem with periodic boundary conditions, and realize this extending by applying Fast Fourier Transformation (FFT) algorithm to the spectral decomposition of the block circulant with circulant blocks (BCCB) matrices. Experimental results confirm the superiority of our new method. [ABSTRACT FROM AUTHOR]

This paper introduces a three-dimensional model for the steady-state response of a pavement-subgrade-soft ground system subjected to moving traffic load. A semi-analytical wave propagation model is introduced which is subjected to four rectangular moving loads and based on a calculation method of the dynamic stiffness matrix of the ground. In order to model a complete road system, the effect of a simple road model is taken into account including pavement, subgrade and soft subsoil. The pavement and the subgrade are regarded as two elastic layers resting on a poroelastic half-space soil medium. The priority has been given to a simple formulation based on the principle of spatial Fourier transforms compatible with good numerical efficiency and yet providing quick solutions. The frequency wave-number domain solution of the road system is obtained by the compatibility condition at the interface of the structural layers. By introducing FFT (Fast Fourier Transform) algorithm, the numerical results are derived and the influences of the observation coordinates, the load speed and excitation frequency, the permeability of the soft subsoil, and the rigidity of the subgrade on the response of the pavement-subgrade-soft ground system are investigated. The numerical results show that the influences of these parameters on the dynamic response of the road system are significant. [ABSTRACT FROM AUTHOR]

Secret sharing schemes (SSS) are very important, because they are used in critical applications such as e-voting, cryptographic key distribution and sharing, secure online auctions, information hiding, and secure multiparty computation. We explained some popular algorithms of secret sharing such as threshold, graph, and visual schemes and their access structures. Besides, we discussed the limitations of those available schemes. Additionally, we proposed a novel threshold secret sharing scheme based on Fast Fourier Transform (FFT) algorithm, which is used for the first time in this paper in the field of secret sharing. That is, we exploited the robust characteristics of FFT such as linearity, reversibility, efficiency, that has time complexity of O(n log n), and it provided us with a wider field, complex numbers. The presented scheme is ideal; the share's size is smaller than the secret and very secure because it depends on solving a linear system of equations generated by FFT. Thus, Our SSS combines the merits of Shamir and Blakley schemes. [ABSTRACT FROM AUTHOR]

Abstract: For automatic speech recognition (ASR), the research centers mainly on algorithm of improving robust, researchers put less emphasis on realization and application of better speech algorithm. Real-time proceeding of speech recognition directly influence on its application, so real-time proceeding of speech recognition is as important as study of algorithm. Speech transform domain method is a necessary technique of speech recognition, so real-time analysis of transform domain method is necessary. In transform domain methods, the short-time spectrum analysis is simple and easy to realize, especially the short-time FFT algorithm is applied to the short-time spectrum analysis. FFT algorithm reduces multiplications greatly. For the purpose, this paper presents short-time spectrum analysis of real-time sampling speech based on FFT algorithm. We use DSP TMS320VC5416 chip and speech codec ASIC TLV320AIC23 as hardware, the real-time speech signal is acquired by ASIC TLV320AIC23. When working frequency of TMS320VC5416 is set 160MHz and sampling frequency is 44.1kHz, the short-time FFT is radix-2 DIF-FFT algorithm and the length of short-time window is 128, the simulation waves and data show that the shorttime FFT algorithm analysis based on TMS320VC5416 chip can meet real-time of system. For estimation of proceeding error, we make a calculation of radix-2 DIT-IFFT. Comparing the result of DIT-IFFT and sampling speech data, error is less than 10-3. [Copyright &y& Elsevier]

Wireless broadband (WiBro) systems can provide high data rate wireless internet access with personal subscriber station under the stationary or mobile environment. It is the orthogonal frequency division multiple access (OFDMA) in time division duplex (TDD) system with 768 useful subcarriers over a nominal bandwidth of 8.75 MHz at 2.3 GHz band and each frame is composed of 42 OFDM symbols, corresponding to 5ms. For modulation and demodulation in the WiBro communication system, the fourier fast transform (FFT) processing is the most speed and power consumption critical path. In this paper, we describe 4096 points FFT and inverse FFT processor for mobile in-car entertainment systems. To obtain low complexities, small computation power and distributed memory, partially operated over-sampling architecture is developed to meet the requirement of non-stopping and high-speed data throughput. From experiment results, we can show that our methods reduce the complexity about 3 7.8% and it is suitable to implementation in mobile devices for WiBro consumer application which is required small area and low-power such as multimedia data service. [ABSTRACT FROM AUTHOR]

In this paper, two fourth-order accurate compact difference schemes are presented for solving the Helmholtz equation in two space dimensions when the corresponding wave numbers are large. The main idea is to derive and to study a fourth-order accurate compact difference scheme whose leading truncation term, namely, the O(h4) term, is independent of the wave number and the solution of the Helmholtz equation. The convergence property of the compact schemes are analyzed and the implementation of solving the resulting linear algebraic system based on a FFT approach is considered. Numerical results are presented, which support our theoretical predictions. [ABSTRACT FROM AUTHOR]

An alternative way of refining phases with the origin-free modulus sum function S is shown that, instead of applying the tangent formula in sequential mode [Rius (1993). Acta Cryst. A 49, 406–409], applies it in parallel mode with the help of the fast Fourier transform (FFT) algorithm. The test calculations performed on intensity data of small crystal structures at atomic resolution prove the convergence and hence the viability of the procedure. This new procedure called S-FFT is valid for all space groups and especially competitive for low-symmetry ones. It works well when the charge-density peaks in the crystal structure have the same sign, i.e. either positive or negative. [ABSTRACT FROM AUTHOR]

Abstract: The thick film photoresist lithography is a much more complicated process compared to the thin film photoresist lithography. In this paper, we have developed a new model for lithography of thick film photoresist by using the angular spectrum theory. The thick film photoresist is divided into many homogeneous layers, and the diffractive optical imaging distribution in photoresist is regarded as superposition of different spectrum plane waves. Propagation of each plane wave is determined by the optical transfer function, and the propagation direction, amplitude and phase are dominated by reflection and transmission between each interface of the sub-layers. The fast Fourier transform (FFT) has been converted into a convolution calculation to keep the computation accurate and reduce computation cost. Numerical calculation results show that optical intensity in cross-sect of thick film resist is strongly affected by reflection, transmission on interface and variation of dielectric permittivity along direction of depth, and therefore these factors should be considered while analyzing diffractive imaging field in thick film photoresist. [Copyright &y& Elsevier]

Georeferencing images is a laborious process so schemes for automating this process have been under investigation for some time. Among the most promising automatic registration algorithms are those based on the fast Fourier transform (FFT). The displacement between two given images can be determined by computing the ratio F1 conj(F2)/|F1F2|, and then applying the inverse Fourier transform. The result is an impulse-like function, which is approximately zero everywhere except at the displacement that is necessary to optimally register the images. Converting from rectangular coordinates to log-polar coordinates, shifts representing rotation and scaling can also determined to complete the georectification process. A FFT-based algorithm has been successfully implemented in Interactive Data Language (IDL) and added as two user functions to an image processing software package—ENvironment for Visualizing Images (ENVI) interface. ENVI handles all pre- and post-processing works such as input, output, display, filter, analysis, and file management. To test this implementation, several dozen tests were conducted on both simulated and “real world” images. The results of these tests show advantages and limitations of this algorithm. In particular, our tests show that the accuracy of the resulting registration is quite good compared to current manual methods. [Copyright &y& Elsevier]

THz Atmospheric Limb Sounder (TALIS) is a microwave radiometer designed by the National Space Science Center of the Chinese Academy of Sciences (NSSC, CAS) for measuring the vertical distribution of temperature and chemical constituents in the middle and upper atmosphere. The digital spectrometer is an important part of TALIS' back end, which mainly realizes the function of spectral analysis. The radix 16 real-time complex fast Fourier transform (FFT) algorithm used in the digital spectrometer was obtained by improving and combining the parallel processing and complex processing of the FFT algorithm. In this study, the digital spectrometer parameter selection is systematically presented, and the effect of the digital spectrometer FFT algorithm on the TALIS system sensitivity is analyzed based on the TALIS system simulation model we established in the previous stage of this research. The results show that the actual full-band sensitivity obtained after using the FFT algorithm is consistent with the ideal full-band sensitivity of TALIS for different integration time, spectral resolutions, and quantization bits. However, the results of the comparison of the actual sub-band sensitivity after using the FFT algorithm with the ideal sub-band sensitivity show that the deterioration of the sub-band sensitivity will be caused by the FFT algorithm. The mean value of the deterioration ratio was found to be approximately 18%, and the maximum value of the deterioration ratio was approximately 33%. [ABSTRACT FROM AUTHOR]

A decimation-in-time radix-2 fast Fourier transform (FFT) algorithm is considered here for implementation in multiprocessors with shared bus, multistage interconnection network (MIN), and in mesh connected computers. Results are derived for dab allocation, interprocessor communication, approximate computation time, and speedup of an N point FF1 on any F available processing elements (PE's). Further generalization is obtained for a radix-r FFT algorithm. An N × N point two-dimensional discrete Fourier transform (DFT) implementation is also considered when one or more rows of the input data matrix are allocated to each PE. A performance comparison is carried out mainly between a shared bus multiprocessor and a computer with multistage interconnection network. It is shown that the latter gives much higher speedup for F > 16 and is more cost effective even with the high cost of switches. N, P and r, considered here, are all powers of two. [ABSTRACT FROM AUTHOR]

A rapidly convergent series-the Chebyshev-Bessel series for representation of the physical optics (PO) radiation integral is developed, which is applicable to evaluating radiated field of reflector antennas. [ABSTRACT FROM AUTHOR]

A renewed methodology for simulating two-spatial dimensional stochastic wind field is addressed in the present study. First, the concept of cross wavenumber spectral density (WSD) function is defined on the basis of power spectral density (PSD) function and spatial coherence function to characterize the spatial variability of the stochastic wind field in the two-spatial dimensions. Then, the hybrid approach of spectral representation and wavenumber spectral representation and that of proper orthogonal decomposition and wavenumber spectral representation are respectively derived from the Cholesky decomposition and eigen decomposition of the constructed WSD matrices. Immediately following that, the uniform hybrid expression of spectral decomposition and wavenumber spectral representation is obtained, which integrates the advantages of both the discrete and continuous methods of one-spatial dimensional stochastic field, allowing for reflecting the spatial characteristics of large-scale structures. Moreover, the dimension reduction model for two-spatial dimensional stochastic wind field is established via adopting random functions correlating the high-dimensional orthogonal random variables with merely 3 elementary random variables, such that this explicitly describes the probability information of stochastic wind field in probability density level. Finally, the numerical investigations of the two-spatial dimensional stochastic wind fields respectively acting on a long-span suspension bridge and a super high-rise building are implemented embedded in the FFT algorithm. The validity and engineering applicability of the proposed method are thus fully verified, providing a potentially effective approach for refined wind-resistance dynamic reliability analysis of large-scale complex engineering structures. • The hybrid approach is proposed for two-spatial dimensional stochastic wind field. • The proposed hybrid approach reflects the characteristics of large-scale structures. • A dimension reduction model is suggested, with only 3 elementary random variables. • The FFT algorithm can be introduced to enhance the numerical simulation efficiency. [ABSTRACT FROM AUTHOR]

The Letter presents a method for the rigorous analysis of the microstrip Yagi antenna. Using the mixed potential integral equation (MPIE) for patch antennas, the FFT algorithm and the biconjugate gradient iterative method, the solution for the unknown current distribution on the patch is obtained in an efficient manner without requiring the storage of large matrices that typically arise in moment-method computations. Consequently, the scheme can deal with patches of arbitrary shapes and can handle a very large number of unknowns. Numerical results of input impedance and radiation patterns are compared with measured results. [ABSTRACT FROM AUTHOR]