In the practical environment,it is very common for the simultaneous occurrence of base excitation and crosswind.Scavenging the combined energy of vibration and wind with a single energy harvesting structure is fascina...In the practical environment,it is very common for the simultaneous occurrence of base excitation and crosswind.Scavenging the combined energy of vibration and wind with a single energy harvesting structure is fascinating.For this purpose,the effects of the wind speed and random excitation level are investigated with the stochastic averaging method(SAM)based on the energy envelope.The results of the analytical prediction are verified with the Monte-Carlo method(MCM).The numerical simulation shows that the introduction of wind can reduce the critical excitation level for triggering an inter-well jump and make a bi-stable energy harvester(BEH)realize the performance enhancement for a weak base excitation.However,as the strength of the wind increases to a particular level,the influence of the random base excitation on the dynamic responses is weakened,and the system exhibits a periodic galloping response.A comparison between a BEH and a linear energy harvester(LEH)indicates that the BEH demonstrates inferior performance for high-speed wind.Relevant experiments are conducted to investigate the validity of the theoretical prediction and numerical simulation.The experimental findings also show that strong random excitation is favorable for the BEH in the range of low wind speeds.However,as the speed of the incoming wind is up to a particular level,the disadvantage of the BEH becomes clear and evident.展开更多
A one-step band-limited extrapolation procedure is systematically developed under an a priori assumption of bandwidth. The rationale of the proposed scheme is to expand the known signal segment based on a band-limited...A one-step band-limited extrapolation procedure is systematically developed under an a priori assumption of bandwidth. The rationale of the proposed scheme is to expand the known signal segment based on a band-limited basis function set and then to generate a set of Empirical Orthogonal Functions (EOF’s) adaptively from the sample values of the band-limited function set. Simulation results indicate that, in addi- tion to the attractive adaptive feature, this scheme also appears to guarantee a smooth result for inexact data, thus suggesting the robustness of the proposed procedure.展开更多
As is well known, coherence does not distinguish the relative phase of a pair of real, sinusoidal time series;the coherence between them is always unity. This behavior can limit the applicability of coherence analysis...As is well known, coherence does not distinguish the relative phase of a pair of real, sinusoidal time series;the coherence between them is always unity. This behavior can limit the applicability of coherence analysis in the special case where the time series are band-limited (nearly-monoch- romatic) and where sensitivity to phase differences is advantageous. We propose a simple mod-ification to the usual formula for coherence in which the cross-spectrum is replaced by its real part. The resulting quantity behaves similarly to coherence, except that it is sensitive to relative phase when the signals being compared are strongly band-limited. Furthermore, it has a useful interpretation in terms of the zero-lag cross-correlation of real band-passed versions of the time series.展开更多
Multi-channel sampling for band-limited signals is fundamental in the theory of multi-channel parallel A/D environment and multiplexing wireless communication environment. As the fractional Fourier transform has been ...Multi-channel sampling for band-limited signals is fundamental in the theory of multi-channel parallel A/D environment and multiplexing wireless communication environment. As the fractional Fourier transform has been found wide applications in signal processing fields, it is necessary to consider the multi-channel sampling theorem based on the fractional Fourier transform. In this paper, the multi-channel sampling theorem for the fractional band-limited signal is firstly proposed, which is the generalization of the well-known sampling theorem for the fractional Fourier transform. Since the periodic nonuniformly sampled signal in the fractional Fourier domain has valuable applications, the reconstruction expression for the periodic nonuniformly sampled signal has been then obtained by using the derived multi-channel sampling theorem and the specific space-shifting and phase-shifting properties of the fractional Fourier transform. Moreover, by designing different fractional Fourier filters, we can obtain reconstruction methods for other sampling strategies.展开更多
In this paper, we present some new algorithms to reconstruct multivariate band-limited functionsfrom irregular sampled values, which allow more arbitrary sampling points and lower sampling densities thanknown results.
A normalized two-dimensional band-limited Weierstrass fractal function is used for modelling the dielectric rough surface. An analytic solution of the scattered field is derived based on the Kirchhoff approximation. T...A normalized two-dimensional band-limited Weierstrass fractal function is used for modelling the dielectric rough surface. An analytic solution of the scattered field is derived based on the Kirchhoff approximation. The variance of scattering intensity is presented to study the fractal characteristics through theoretical analysis and numerical calculations. The important conclusion is obtained that the diffracted envelope slopes of scattering pattern can be approximated as a slope of linear equation. This conclusion will be applicable for solving the inverse problem of reconstructing rough surface and remote sensing.展开更多
An increasing demand for high data rate transmission and protection over bandlimited channels with severe inter-symbol interference has resulted in a flurry of activity to improve channel equalization, In conjunction ...An increasing demand for high data rate transmission and protection over bandlimited channels with severe inter-symbol interference has resulted in a flurry of activity to improve channel equalization, In conjunction with equalization, channel coding-decoding can be employed to improve system performance. In this letter, the performance of the three stage turbo-equalization-decoding employing log maximum a posteriori probability is experimentally evaluated by a fading simulator. The BER is evaluated using various information sequence and interleaver sizes taking into account that the communication medium is a noisy inter symbol interference channel.展开更多
Shannon sampling theorem is the basic theorem in signal reconstruction based ondiscrete sampling values in communication theory. The convergence rate of thisformula, however, is very slow. Professor Pen Rui-reng. afte...Shannon sampling theorem is the basic theorem in signal reconstruction based ondiscrete sampling values in communication theory. The convergence rate of thisformula, however, is very slow. Professor Pen Rui-reng. after some slight compromiseon sampling rate, has come to the 3rd order, the 4th order and the 5th order samplingformulae. The calculation of the third order formula on the computer proves that itconverges much faster than the Shannon formula. This paper gives a general methodto comstruct a higher order sampling formula.展开更多
The aim of the present paper is to state an asymptotic property Ρ of Shannon’s sampling theorem type, based on normalized cardinal sines, and keeping constant the sampling frequency of a not necessarilly band...The aim of the present paper is to state an asymptotic property Ρ of Shannon’s sampling theorem type, based on normalized cardinal sines, and keeping constant the sampling frequency of a not necessarilly band- limited signal. It generalizes in the limit the results stated by Marvasti et al. [7] and Agud et al. [1]. We show that Ρ is fulfilled for any constant signal working for every given sampling frequency. Moreover, we conjecture that Gaussian maps of the form e-Λt2 ,Λ∈R+, hold Ρ. We support this conjecture by proving the equality given by for the three first coefficients of the power series representation of e-Λt2 .展开更多
We present a novel configuration for carrier suppressed return-to-zero (CSRZ) signal generation, which only requires a single stage Mach-Zehnder (MZ) modulator in conjunction with an electrical mixer. Electrical band-...We present a novel configuration for carrier suppressed return-to-zero (CSRZ) signal generation, which only requires a single stage Mach-Zehnder (MZ) modulator in conjunction with an electrical mixer. Electrical band-limiting is also introduced to increase dispersion tolerance without causing additional penalty due to nonlinear effects in long haul dense wavelength division multiplexed (DWDM) CSRZ systems using conventional launch power levels.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.12272355,1202520411902294)+1 种基金the Opening Foundation of Shanxi Provincial Key Laboratory for Advanced Manufacturing Technology of China(No.XJZZ202304)the Shanxi Provincial Graduate Innovation Project of China(No.2023KY629)。
文摘In the practical environment,it is very common for the simultaneous occurrence of base excitation and crosswind.Scavenging the combined energy of vibration and wind with a single energy harvesting structure is fascinating.For this purpose,the effects of the wind speed and random excitation level are investigated with the stochastic averaging method(SAM)based on the energy envelope.The results of the analytical prediction are verified with the Monte-Carlo method(MCM).The numerical simulation shows that the introduction of wind can reduce the critical excitation level for triggering an inter-well jump and make a bi-stable energy harvester(BEH)realize the performance enhancement for a weak base excitation.However,as the strength of the wind increases to a particular level,the influence of the random base excitation on the dynamic responses is weakened,and the system exhibits a periodic galloping response.A comparison between a BEH and a linear energy harvester(LEH)indicates that the BEH demonstrates inferior performance for high-speed wind.Relevant experiments are conducted to investigate the validity of the theoretical prediction and numerical simulation.The experimental findings also show that strong random excitation is favorable for the BEH in the range of low wind speeds.However,as the speed of the incoming wind is up to a particular level,the disadvantage of the BEH becomes clear and evident.
文摘A one-step band-limited extrapolation procedure is systematically developed under an a priori assumption of bandwidth. The rationale of the proposed scheme is to expand the known signal segment based on a band-limited basis function set and then to generate a set of Empirical Orthogonal Functions (EOF’s) adaptively from the sample values of the band-limited function set. Simulation results indicate that, in addi- tion to the attractive adaptive feature, this scheme also appears to guarantee a smooth result for inexact data, thus suggesting the robustness of the proposed procedure.
文摘As is well known, coherence does not distinguish the relative phase of a pair of real, sinusoidal time series;the coherence between them is always unity. This behavior can limit the applicability of coherence analysis in the special case where the time series are band-limited (nearly-monoch- romatic) and where sensitivity to phase differences is advantageous. We propose a simple mod-ification to the usual formula for coherence in which the cross-spectrum is replaced by its real part. The resulting quantity behaves similarly to coherence, except that it is sensitive to relative phase when the signals being compared are strongly band-limited. Furthermore, it has a useful interpretation in terms of the zero-lag cross-correlation of real band-passed versions of the time series.
基金Supported partially by the National Natural Science Foundation of China (Grant Nos. 60232010 and 60572094) the National Natural Science Foundation of China for Distinguished Young Scholars (Grant No. 60625104)
文摘Multi-channel sampling for band-limited signals is fundamental in the theory of multi-channel parallel A/D environment and multiplexing wireless communication environment. As the fractional Fourier transform has been found wide applications in signal processing fields, it is necessary to consider the multi-channel sampling theorem based on the fractional Fourier transform. In this paper, the multi-channel sampling theorem for the fractional band-limited signal is firstly proposed, which is the generalization of the well-known sampling theorem for the fractional Fourier transform. Since the periodic nonuniformly sampled signal in the fractional Fourier domain has valuable applications, the reconstruction expression for the periodic nonuniformly sampled signal has been then obtained by using the derived multi-channel sampling theorem and the specific space-shifting and phase-shifting properties of the fractional Fourier transform. Moreover, by designing different fractional Fourier filters, we can obtain reconstruction methods for other sampling strategies.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos. 10171050, 10201014) the Mathematical Tianyuan Foundation(Grant No. TY10126007) the Research Fund for the Doctoral Program of Higher Education, and the Liuhui Cen
文摘In this paper, we present some new algorithms to reconstruct multivariate band-limited functionsfrom irregular sampled values, which allow more arbitrary sampling points and lower sampling densities thanknown results.
基金supported by the National Natural Science Foundation of China (Grant No 60571058)Specialized Research Fund for the Doctoral Program of Higher Education, China (Grant No 20070701010)
文摘A normalized two-dimensional band-limited Weierstrass fractal function is used for modelling the dielectric rough surface. An analytic solution of the scattered field is derived based on the Kirchhoff approximation. The variance of scattering intensity is presented to study the fractal characteristics through theoretical analysis and numerical calculations. The important conclusion is obtained that the diffracted envelope slopes of scattering pattern can be approximated as a slope of linear equation. This conclusion will be applicable for solving the inverse problem of reconstructing rough surface and remote sensing.
基金the National Natural Science Foundation of China(No.60172048)
文摘An increasing demand for high data rate transmission and protection over bandlimited channels with severe inter-symbol interference has resulted in a flurry of activity to improve channel equalization, In conjunction with equalization, channel coding-decoding can be employed to improve system performance. In this letter, the performance of the three stage turbo-equalization-decoding employing log maximum a posteriori probability is experimentally evaluated by a fading simulator. The BER is evaluated using various information sequence and interleaver sizes taking into account that the communication medium is a noisy inter symbol interference channel.
文摘Shannon sampling theorem is the basic theorem in signal reconstruction based ondiscrete sampling values in communication theory. The convergence rate of thisformula, however, is very slow. Professor Pen Rui-reng. after some slight compromiseon sampling rate, has come to the 3rd order, the 4th order and the 5th order samplingformulae. The calculation of the third order formula on the computer proves that itconverges much faster than the Shannon formula. This paper gives a general methodto comstruct a higher order sampling formula.
基金partially supported by MCI(Ministerio de Ciencia e Innovacion)and FEDER(Fondo Europeo Desarrollo Regional),grant number MTM2008--03679/MTMFundacion Seneca de la Region de Murcia,grant number 08667/PI/08JCCM(Junta de Comunidades de Castilla-La Mancha),grant number PEII09-0220-0222.
文摘The aim of the present paper is to state an asymptotic property Ρ of Shannon’s sampling theorem type, based on normalized cardinal sines, and keeping constant the sampling frequency of a not necessarilly band- limited signal. It generalizes in the limit the results stated by Marvasti et al. [7] and Agud et al. [1]. We show that Ρ is fulfilled for any constant signal working for every given sampling frequency. Moreover, we conjecture that Gaussian maps of the form e-Λt2 ,Λ∈R+, hold Ρ. We support this conjecture by proving the equality given by for the three first coefficients of the power series representation of e-Λt2 .
文摘We present a novel configuration for carrier suppressed return-to-zero (CSRZ) signal generation, which only requires a single stage Mach-Zehnder (MZ) modulator in conjunction with an electrical mixer. Electrical band-limiting is also introduced to increase dispersion tolerance without causing additional penalty due to nonlinear effects in long haul dense wavelength division multiplexed (DWDM) CSRZ systems using conventional launch power levels.
