By displaying the change of signal energy on a two dimensional time-frequency images based on time-frequency analysis, a new mathematical morphology method to distinguish target from the nonlinear time-frequency curve is presented.

A novel approach to detect abnormal transient vibration signal for complex mechanical system is presented,where alias-free exponential bilinear time-frequency transformation is adopted to avoid the frequency alias and information loss in the traditional bilinear distributions. Simultancously,the cross-terms are effectively deduced with higher time-frequency resolution,which is validated by a gearbox early fault detection.

The scattering function is one of most important mathematical method describing time-frequency dispersion channel performance, which embodies a concentrated reflection of the dispersion characteristics of the mobile radio channel in time and frequency domain, and reflects the angle dispersion distributed performance of the channel to a certain extent.

Future broadband wireless communication systems should be able to provide reliable high-data-rate transmissions at low cost in time and frequency selective wireless channel.

Aimed at all kinds of methods of time-frequency analysis currently,this paper emphasizes on introducing the HHT method ,which deeply depicts the relationship between time and frequency and gets the time-frequency-energy figure of the analysed signal using the integration of EMD and Hilbert transform.

Wavelet analysis is a new mathematical method and has acquired wide application in the field due to its fine character of making analysis according to multiple resolutions in time and frequency domains.

The characteristics of the urban heat island(UHI) intensity in Shanghai were studied and calculated using wavelet transformation, based on per hour difference in temperatures in 2000 observed from Davis automatic stations installed at the Urban and Suburb of Shanghai.

We present two-sided singular value estimates for a class of convolution-product operators related to time-frequency localization.

The Balian-Low theorem (BLT) is a key result in time-frequency analysis, originally stated by Balian and, independently, by Low, as: If a Gabor system $\{e^{2\pi imbt} \, g(t-na)\}_{m,n \in \mbox{\bf Z}}$

Gabor Time-Frequency Lattices and the Wexler-Raz Identity

Gabor time-frequency lattices are sets of functions of the form $g_{m \alpha , n \beta} (t) =e^{-2 \pi i \alpha m t}g(t-n \beta)$ generated from a given function $g(t)$ by discrete translations in time and frequency.

High-Order Orthonormal Scaling Functions and Wavelets Give Poor Time-Frequency Localization

Gabor time-frequency lattices are sets of functions of the form $g_{m \alpha , n \beta} (t) =e^{-2 \pi i \alpha m t}g(t-n \beta)$ generated from a given function $g(t)$ by discrete translations in time and frequency.

We present an explicit, straightforward construction of smooth integrable functions with prescribed gaps around the origin in both time and frequency domain.

From the analysis of the electric field structure the conclusion is drawn that the bulk of the AKR power is carried by the signal component fast variable in time and frequency (flickering component).

The spectrometer provides the programming of time and frequency parameters of pulse sequences and allows phase-sensitive detection of echo signals with their subsequent representation in digital form.

Experimental data are presented on time and frequency dependences of the reverberation level for bistatic transmission and reception at low acoustic frequencies.

The equipment is aimed at manipulating five sectionalizing posts and provided with both, telecontrol and telesignaling. Time-frequency system is employed for the channel. Telesignaling from the five sectionalizing posts works continually and automatically in cyclic order. Self-checking duel information codes are adopted for each operation, in which the direct code is being compared with its inverse counterpart. The logic design is suitable for use, the circuitry is simple, and the equipment is reliable and easy...

The equipment is aimed at manipulating five sectionalizing posts and provided with both, telecontrol and telesignaling. Time-frequency system is employed for the channel. Telesignaling from the five sectionalizing posts works continually and automatically in cyclic order. Self-checking duel information codes are adopted for each operation, in which the direct code is being compared with its inverse counterpart. The logic design is suitable for use, the circuitry is simple, and the equipment is reliable and easy in maintenance.

126 lateral geniculate neurones were examined on unanaesthetized immobili-zed cats.The temporal frequency tuning curves of single neurones were measuredby stimulating the cat's eye with a sinusoidally modulated light spot,generated ona CRT and presented to each neurone's receptive field center or its surround.Theaverage discharging rate was used as an index to judge the sensitivity to different mo-dulating frequencies.By comparing the mean impulse rates responding to modula-ted light stimulations(modulated discharge...

126 lateral geniculate neurones were examined on unanaesthetized immobili-zed cats.The temporal frequency tuning curves of single neurones were measuredby stimulating the cat's eye with a sinusoidally modulated light spot,generated ona CRT and presented to each neurone's receptive field center or its surround.Theaverage discharging rate was used as an index to judge the sensitivity to different mo-dulating frequencies.By comparing the mean impulse rates responding to modula-ted light stimulations(modulated discharge rate)with those responding to unmodulatedlight(unmodulated discharge rate),two opposite effects were observed.The majorityof the cells(93.7)% showed modulation-excitatory curves in which the modulateddischarge rates were higher than the unmodulated ones.A minority of the cells(6.3%)showed modulation-inhibitory curves in which the modulated dischargerates were lower than the unmodulated ones.The modulation-excitatory curvescould further be grouped into two subtypes,the“band-pass filters”and the“low-pass filters”.Similarly,the modulation-inhibitory curves could also be dividedinto two subtypes,the“band-rejection filters”and the“low-rejection filters”.Onboth sides of the temporal frequency tuning curve subsidiary sidebands oppositein direction to the main part of the curves could often be seen,i.e.inhibitorysidebands flanking the modunation-excitatory tuning curve and excitatorysidebands flanking the modulation-inhibitory tuning curve.Most of the tuningcurves have only one peak.of the 110 curves measured the peak loci show anormal distribution which centered at 7 Hz.The tuning curves due to stimulationof different locations of the periphery were almost the same.But the tuningproperties of the receptive field centers were different from those of the periphe-ries either in shape or in band-width.

This paper makes to model and predict the measured data in Variant Sample Time of Hydrogen, Cesium and Rubidium atomic clocks, mainly according to the principle of ARIMA models of time series analysis method with the Bias function theory of noise Variance of measuring statistics of atomic time/frequency and method of spline functions. Some preliminary useful predicting models and conclusions obtained in variant noise process have pretical sense in optimal predictions and monitoring of the behaviour of atomic...

This paper makes to model and predict the measured data in Variant Sample Time of Hydrogen, Cesium and Rubidium atomic clocks, mainly according to the principle of ARIMA models of time series analysis method with the Bias function theory of noise Variance of measuring statistics of atomic time/frequency and method of spline functions. Some preliminary useful predicting models and conclusions obtained in variant noise process have pretical sense in optimal predictions and monitoring of the behaviour of atomic time/frequency and in developing new optimal filting control method to improve the performances of atomic clocks.