High-speed Digital Image Analysis Research Articles

Mixing/segregation characteristics and bubble behaviors of density-segregated binary particles in a pressurized fluidized bed

To enhance comprehension and achieve more targeted optimization of pressurized fluidized beds, experiments were carried out in a “cold” pseudo 2D pressurized fluidized bed with binary mixtures differing in densities via high-speed digital image analysis. The impacts of operating pressure and gas velocity on fluidization pattern, mixing/segregation characteristics, and bubble behaviors were comprehensively analyzed. Results show that the fluidization of binary mixtures is a gradual process which occurs within the range between the minimum fluidization velocity of flotsam and jetsam components. Particles with lighter density tend to produce larger size of bubbles, larger bubble fraction and increased fluctuation compared to the heavier ones when particle sizes are similar. Increasing the pressure results in an overall decreased bubble diameter and bubble fraction, which prohibits the bubble-particle interaction and ultimately deteriorates the mixing quality. The carried-out whole-field, non-intrusive measurements in this work would provide the much-needed database for validation of CFD models.

Direct tensile behavior of steel fiber reinforced ultra-high performance concrete at high strain rates using modified split Hopkinson tension bar

This paper aims to investigate the dynamic tensile behavior of steel fiber reinforced ultra-high performance concrete (SF-UHPC) under impact loading. The investigated SF-UHPC were designed to have a compressive strength in excess of 200 MPa. A modified split Hopkinson tensile bar (SHTB) has been designed to obtain the dynamic behavior of SF-UHPC with fiber volume fraction of 2% and 4% under high strain rates ranging from 55 to 156 s−1. Wave shaping technique was used to achieve stress equilibrium and constant strain rate during testing. The average dynamic impact factor (DIF) of the tensile strength for SF-UHPC with a fiber volume fraction of 2% and 4% was found to be 3.2 and 1.9 at an average strain rate of 118 s−1 and 131 s−1, respectively. The designed SHTB in combination with high speed digital image analysis of notched specimens was able to measure the stress versus crack opening relationship of the SF-UHPC. Based on the results obtained from the current study and results obtained from twelve other studies, an equation is suggested to calculate the DIF of the tensile strength of SF-UHPC.

Transferencia de oxígeno en una columna de tres fases utilizando polímeros sólidos como vectores de transferencia de masa

Three solid polymers; Kraton, Elvax, and Desmopan, previously suggested to be used in three-phase reactors, were evaluated for their ability to enhance oxygen transfer in a bubble column. These vectors were first characterized through determination of particle size distribution, surface roughness, specific surface area, density, void fraction and thermal stability. Oxygen transfer was then determined with a non-coalescing medium using polymer volume fractions from 0 to 75% in a 4 L bubble column operated at air flow rates ranging from 1 to 6 L/min. The results showed that the oxygen transfer was significantly improved in presence of 10 and 25% of Kraton and Elvax, compared with control experiment with no polymer. A maximum oxygen transfer improvement of 90%, compared with control, was observed with 10% Kraton. With Desmopan, no positive effect on oxygen transfer was observed regardless of the vector percentage used. Phase’s dispersion and oxygen transfer was further explored in presence of 10% Kraton. Gas holdup, Sauter mean bubble diameter and vector dispersion were characterized by means of high speed digital image analysis. The results showed that the enhancement of oxygen transfer mediated by Kraton was mainly caused by an increase of gas holdup and consequently of the gas/liquid surface area.

Multiparametric Analysis of Vocal Fold Vibrations in Healthy and Disordered Voices in High-Speed Imaging

The aim of this study was to look for visual subjective and objective parameters of vocal fold dynamics being capable of differentiating healthy from pathologic voices in daily clinical practice applying endoscopic high-speed digital imaging (HSI). Four hundred ninety-six datasets containing 80 healthy and 416 pathologic subjects (232 functional dysphonia (FD), 13 bilateral, and 171 unilateral vocal fold nerve paralysis) were analyzed retrospectively. Videos at 4000Hz (256×256 pixel) were recorded during sustained phonation. Subjective parameters were visually evaluated and complemented by an analysis of objective parameters. Visual subjective parameters were mucosal wave, glottal closure type, glottal closure insufficiency (GI), asymmetries of the vocal folds, and phonovibrogram (PVG) symmetry. After image segmentation, objective parameters were computed: closed quotient, perturbation measures (PMs) of glottal area, and left-right asymmetry values. HSI evaluation enabled to distinguish healthy from pathologic voices. For visual subjective parameters, GI, symmetrical behavior, and PVG symmetry exhibited statistical significant differences. For 95% of the data, objective parameters could be computed. Among objective parameters, closed quotient, jitter, shimmer, harmonic-to-noise ratio, and signal-to-noise ratio for the glottal area function differentiated statistically significant normal from pathologic voices. Applying linear discriminant analysis by combining visual subjective and objective parameters, accurate classifications were made for 63.2% of the female and 87.5% of the male group for the three-class problem (healthy, FD, and unilateral vocal fold nerve paralysis). Actual acoustically applied PMs can be transferred to clinical beneficial HSI analysis. Combining visual subjective and objective basic parameters succeeds in differentiating pathologic from healthy voices. The presented evaluation can easily be included into everyday clinical practice. However, further research is needed to broaden our understanding of the variability within and across healthy and pathologic vocal fold vibrations for diagnosing voice disorders and therapy control.

Collagen Injection for Correcting Vocal Fold Asymmetry: High-Speed Imaging

We hypothesized that high-speed digital imaging with videokymographic and laryngotopographic analysis would provide a quantitative method to evaluate the effect of collagen injection for the correction of asymmetric and irregular vocal fold vibration in unilateral vocal fold paralysis. Videokymographic and laryngotopographic analysis was performed for high-speed digital recordings of vocal fold vibration for visualizing the glottal vibratory patterns, and for quantifying the frequency of vibration of each vocal fold, respectively, including comparisons between the paralyzed and normal vocal folds before and after surgery. This included prospective observations of 11 subjects with unilateral vocal fold paralysis (4 male, 7 female; mean +/- SD age, 67.1 +/- 12.0 years) using high-speed digital image analysis before and after collagen injection. Analysis of the laryngotopographs revealed 2 distinct frequencies of vibration for the paralyzed and contralateral vocal folds for 8 of the 11 subjects before surgery. After collagen injection, the vibration frequencies became identical, despite asymmetric vibration amplitudes. Asymmetric vibration amplitudes were also observed in the other 3 subjects before surgery, but the amplitudes became symmetric after collagen injection, despite a persistent phase shift. Asymmetric vibration in vocal fold paralysis was exemplified by differences in vibration frequency and amplitude between the vocal folds. The present study showed that after collagen injection, these aspects of vibratory patterns improved toward symmetry. This surgical procedure could improve the functional symmetry of the larynx for phonation.

High-speed digital imaging laryngoscopy of the neoglottis following supracricoid laryngectomy with cricohyoidoepiglottopexy

This study aimed to analyse vocal performance and to investigate the nature of the neoglottal sound source in patients who had undergone supracricoid laryngectomy with cricohyoidoepiglottopexy, using a high-speed digital imaging system. High-speed digital imaging analysis of neoglottal kinetics was performed in two patients who had undergone supracricoid laryngectomy with cricohyoidoepiglottopexy; laryngotopography, inverse filtering analysis and multiline kymography were also undertaken. In case one, laryngotopography demonstrated two vibrating areas: one matched with the primary (i.e. fundamental) frequency (75 Hz) and the other with the secondary frequency (150 Hz) at the neoglottis. In case two, laryngotopography showed two vibrating areas matched with the fundamental frequency (172 Hz) at the neoglottis. The interaction between the two areas was considered to be the sound source in both patients. The waveform of the estimated volume flow at the neoglottis, obtained by inverse filtering analysis, corresponded well to the neoglottal vibration patterns derived by multiline kymography. These findings indicated that the specific sites identified at the neoglottis by the present method were likely to be the sound source in each patient. High-speed digital imaging analysis is effective in locating the sites responsible for voice production in patients who have undergone supracricoid laryngectomy with cricohyoidoepiglottopexy. This is the first study to clearly identify the neoglottal sound source in such patients, using a high-speed digital imaging system.

Neurogenic diplophonia: a high-speed digital image analysis

AbstractHigh-speed digital image analysis was made on five cases with diplophonia. All cases had developed diplophonia associated with unilateral recurrent or superior laryngeal nerve paralysis, the definite diagnosis of which was made electromyographically. It was found that there was a difference in vibratory frequency between the left and right vocal folds in all cases. It appeared that the phase difference between the two folds showed a quasiperiodic variation and, as a result, corresponding quasiperiodic perturbation in voice waveform was induced. Coexistence of the frequency of quasiperiodic perturbation in voice waveform and mean voice frequency appeared to give a perceptual impression of diplophonia. It was considered that mass/tension difference between the left and right vocal folds due to neurogenic laryngeal disorders should be the cause of the phase difference between the two folds.

High-speed digital image analysis of vocal cord vibration in diplophonia

Simultaneous recording of vocal fold vibrations and speech signals were performed with three patients having diplophonia using a high-speed digital image recording system developed by the present authors. All three cases studied (1 case of unilateral paralysis of the recurrent nerve; 2 cases of unilateral paralysis of external branch of the superior laryngeal nerve) showed a difference in the vibratory frequency between the left and right vocal folds. The phase difference between the vocal cords varies with time. When it reaches a certain threshold, the phase difference is reset and the vocal cord movements resumes synchrony. When the movements of the vocal cords are in phase, glottal closure is complete and the excitation pattern in the speech waveform is strong, whereas when the movements are out of phase, glottal closure is incomplete and the excitation pattern is weak, resulting in a quasi-periodic vibration in speech waveform.

Role of the Mauthner Cell in Sensorimotor Integration by the Brain Stem Escape Network

The Mauthner neurons have become synonymous with the C start evasive response of fishes. C starts are a two-part movement pattern. First, the fish bends its body so that it has a C-like profile (stage 1) when viewed from above. Second, the fish rapidly accelerates away from its starting position (stage 2). Until recently, it has been possible to determine the contribution of Mauthner cell activity to the expression of this behavior. In this paper we focus on three of our recent papers that address this issue. Our work combines high-speed digital image analysis of the C start with chronic Mauthner cell and electromyographic recordings, lesions of the Mauthner cells, and stimulation of single Mauthner axons in swimming fishes. This work shows that the firing of the Mauthner cell results in a short-latency body contraction that orients the initial stage of the C start away from the direction of the threatening stimulus. The direction of the escape trajectory, however, is more finely tuned to stimulus angle than can be explained by the firing of just the Mauthner cell and its post-synaptic followers. Precise control of trajectory must, therefore, require participation of other neurons. These neurons together with the Mauthner cell form a system that we term the brain stem escape network. We have identified candidate neurons of this network which can now be studied at the single-cell level. Because of both its accessibility for neurophysiological study and its neuroanatomical simplicity, we assert that the brain stem escape network is a useful preparation for understanding fundamental processes of sensorimotor integration in the brain stem.