Waveform Separation Research Articles

Instantaneous polarization attributes based on an adaptive approximate covariance method

We introduce a method for computing instantaneous-polarization attributes from multicomponent signals. This is an improvement on the standard covariance method (SCM) because it does not depend on the window size used to compute the standard covariance matrix. We overcome the window-size problem by deriving an approximate analytical formula for the cross-energy matrix in which we automatically and adaptively determine the time window. The proposed method uses polarization analysis as applied to multicomponent seismic by waveform separation and filtering.

Triangulating the Peaks of Arterial Pressure

Increased arterial stiffness and excessive pressure pulsatility have emerged as important risk factors for a number of common disorders of aging, including cardiovascular disease, stroke, cognitive impairment, and renal disease. The triple-threat combination of robust associations between arterial stiffness and the foregoing disorders, a marked increase in arterial stiffness with advancing age and the graying of our society, has led to intensive efforts to identify mechanisms that contribute to arterial stiffening and widening pulse pressure to define interventions to prevent or reverse stiffness and potentially reduce the substantial burden of related disease. Wave reflections complicate the task of evaluating arterial hemodynamics and play an unclear role in the foregoing diseases. When the heart ejects, ventricular outflow interacts with characteristic impedance of the proximal aorta to produce the forward pressure wave, which travels down the normally compliant aorta at a finite pulse wave velocity (PWV). When the forward wave encounters impedance mismatch, such as a branch point or a change in diameter or wall properties, a partial reflection occurs. Innumerable reflections arising from locations distributed throughout the arterial tree summate into a remarkably discrete reflected pressure wave with amplitude ≈40% of the incident wave. The summated reflected wave returns to the central aorta in midsystole, creating an inflection point and secondary late systolic pressure rise that often augments central aortic systolic and pulse pressure.1 Variable timing of this retrograde-traveling reflected wave creates regional inequalities in systolic and pulse pressure and, therefore, complicates interpretation of single point pressure measurements, such as standard brachial blood pressure, which may differ from central aortic pressure. Augmentation index (AI), which expresses late systolic pressure augmentation as a percentage of pulse pressure, is frequently used to assess wave reflection (Figure). AI, which depends on both timing and amplitude of the reflected wave, has also been widely …

The waveform separation of displacement current and tunneling current using a scanning vibrating probe

A measuring system that separates the both waveforms of displacement and tunneling current using a scanning vibrating probe is described. In the measuring system, the displacement and tunneling current flow periodically in accordance with the perpendicular vibration of the probe. The external circuit current is measured by oscilloscope and is separated into both waveforms of the displacement and tunneling current by utilizing the phase difference of them. The waveform of the displacement current is also analyzed by assuming the presence of excessive surface charges above the sample. Consequently, we can determine the mean distance between the probe and sample, and the offset voltage which is built up by excessive surface charges and work function difference of the probe and sample.

Particle identification in CsI(Tl) using digital pulse shape analysis

We developed particle identification (PID) in a CsI(Tl) crystal using digital pulse shape analysis. We present the details of the experiment, the data analysis, and the results. Four different methods of digital PID were applied to the same data set: (A) the rise-time inspection, (B) the sampling of the ADC waveform at the time of maximum waveform separation, (C) the charge comparison method with a rectangular integration window, and (D) the charge comparison method with a custom weight function. The performance of the methods A and B, which strongly depends on the bandwidth of the signal, is optimal when the bandwidth is reduced to about 0.5 MHz. The performance of the methods C and D can be only slightly improved by restricting the bandwidth. From among the four methods, the method A provides the poorest particle discrimination, while the method D provides the best. The algorithm D compares favorably with the analog charge comparison method, achieving very good proton/α-particle discrimination at energies as low as about 1 MeV, even though the measurements were carried out at the dynamic range of 35 MeV. Algorithms B, C, and D yield the PID index which is almost independent of particle energy, within the energy limits used in this work. Present results clearly show the power of digital electronics in achieving good particle identification for charged particles measured with large dynamic range.

Speech synthesis using glottal closure instants determined from adaptively-threshold wavelet transforms

A speech synthesis system making use of a pitch-synchronous waveform overlap method to realize stable speech synthesis processing in which pitch shaking is negligible. The present invention is characterized in that glottal closure instants are used as reference points (pitch marks) for overlapping. Since the glottal closure instants can be extracted stably and accurately by using dyadic Wavelet conversion, speech in which pitch shaking is negligible and rumbling sounds are minimized can be synthesized stably. In addition, more flexible waveform separation becomes possible by setting the reference point for overlapping and the reference point for waveform separation to different positions. The extraction of glottal closure instants is performed by searching the local peaks of the dyadic Wavelet conversion, but preferably a threshold value for searching for the local peaks of the dyadic Wavelet conversion is adaptively controlled each time dyadic Wavelet conversion is obtained.

Surface Charactreistics of Polyphenylene Sulfide(PPS) Film Treated by Discharge Plasmas.

Polyphenylene sulfide film was treated with low-temperature oxygen, nitrogen, and argon plasmas; argon sputter etching, and low-temperature helium/argon plasma under atmospheric pressure, and then the surface characteristics were investigated by means of critical surface tension and ESCA measurement. Critical surface tension and the O 1S intensities in ESCA spectra were increased considerably after discharge treatments. By helium/argon atmospheric low-temperature plasma treatment, the N 1S and O 1S intensities increased remarkably. From wave form separation of C 1S and S 2p spectra, it was found that oxygens incorporated in the polymer are present in the forms of -C-O-, -COO-, -S(=0)-, and -S(=0) 2−

An EMG analysis of sequential control cycles of articulatory activity during / ǝp Vp/ utterances

Articulatory gestures are executed by a sequence of motor commands to various speech muscles. Owing to motor programs stored in a coordination control subsystem, temporal patterns of the commands are autonomically generated when gestural target information is input. This study is aimed at examining such motor programs for coordinated speech gestures by observing sequential changes in motor commands to several speech muscles. A waveform separation technique was applied to analyze ensemble average waveforms of integrated electromyographic (EMG) signals. The EMG data used in this study contain four extrinsic and two accessory tongue muscles, the orbicularis oris, and the cricothyroid, which were recorded during production of /ǝpVp/ word utterances having 11 English vowels. The results demonstrate synchronized activities of several muscles for /p/ closures, while synergistic and reciprocal types of coordination control are found among tongue muscles during vowel segments. These results are interpreted to compose a motor score for observing sequential control cycles of motor commands to the muscles.

Real-time waveform analysis of multichannel nerve impulses with a multimicroprocessor system.

A new system for the online real-time waveform separation of the nerve impulses recorded from multichannel extracellular electrodes placed to the peripheral nerve trunk has been developed using two microprocessors and a graphics computer. One microprocessor (Intel 8085) performs nerve impulse detection and the other (Intel 8086) separates nerve impulses by clustering in the two-dimensional histograms representing the distribution of the parameters extracted from their waveforms. System performance was examined with two channel impulses recorded from the nerve trunk innervating the Sartorius muscle of a frog. These data could be classified into 6–8 different groups in real time.