A New Failure Criterion for Woven-roving GFRE Thick Tube Subjected to Combined Fatigue Bending Moments and Internal hydrostatic Pressure

Choosing the suitable failure criterion represents the main target for many researchers working with materials, and it represents the first step for new materials before being used in the field. Considering composite materials, specifically, makes it more challenging, because of their very special behavior and characteristics. Besides, it must be noted that, the suitability of a certain criterion differs greatly according to the tested material, and its stress state. Thick-walled tubular specimens, made from wovenroving Glass Fiber- Reinforced Epoxy (GFRE) with two fiber orientations, [0o ,90o ]3s and [±45o ]3s, and two manufacture methods M1 and M2 to prepare the test specimens, were tested under combined fatigue bending and Internal hydrostatic Pressure at different pressure ratios (Pr), PPrr= 00, 00.2222, 00.55, 00.7777 (i.e. pressures amounting to 0%, 25%, 50% and 75% of the burst pressure). The [0o ,90o ]3s specimens were found to have higher bending strength than the [±45o ]3s specimens, at all pressure ratios; This is due to the fiber orientation [0,90°]3s has a minimum value of stress component σ6 which equal to zero. For both fiber orientations [0o ,90o ]3s and [±45o ]3s and both manufacture methods M1 and M2, were found none of the available criteria succeeded in predicting failure for the studied case, this due to the effect of hoop stress on values of amplitude component and the corresponding fatigue strength; consequently. A new modifying term was introduced that made Norris-Distortional, Tsai-Hahn, and Tsai-Hill criteria suitable for this studied case, resulting in a new criterion

Understanding phase-amplitude coupling from bispectral analysis

Two measures of cross-frequency coupling (CFC) are Phase-Amplitude Coupling (PAC) and bicoherence. The estimation of PAC with meaningful bandwidth for the high frequency amplitude is crucial in order to avoid misinterpretations. While recommendations on the bandwidth of PAC’s amplitude component exist, there is no consensus yet. Here, we show that the earlier recommendations on filter settings lead to estimates which are smeared in the frequency domain, which makes it difficult to distinguish higher harmonics from other types of CFC. We also show that smearing can be avoided with a different choice of filter settings by theoretically relating PAC to bicoherence. To illustrate this, PAC estimates of simulations and empirical data are compared to bispectral analyses. We used simulations replicated from an earlier study and empirical data from human electro-encephalography and rat local field potentials. PAC’s amplitude component was estimated using a bandwidth with a ratio of (1) 2:1, (2) 1:1, or (3) 0.5:1 relative to the frequency of the phase component. For both simulated and empirical data, PAC was smeared over a broad frequency range and not present when the estimates comprised a 2:1- and 0.5:1-ratio, respectively. In contrast, the 1:1-ratio accurately avoids smearing and results in clear signals of CFC. Bicoherence estimates, which do not smear across frequencies by construction, were found to be essentially identical to PAC calculated with the recommended frequency setting.

When a period is not a full stop: Light-curve structure reveals fundamental parameters of Cepheid and RR Lyrae stars

ABSTRACT The period of pulsation and the structure of the light curve for Cepheid and RR Lyrae variables depend on the fundamental parameters of the star: mass, radius, luminosity, and effective temperature. Here, we train artificial neural networks on theoretical pulsation models to predict the fundamental parameters of these stars based on their period and light-curve structure. We find significant improvements to estimates of these parameters made using light-curve structure and period over estimates made using only the period. Given that the models are able to reproduce most observables, we find that the fundamental parameters of these stars can be estimated up to 60 per cent more accurately when light-curve structure is taken into consideration. We quantify which aspects of light-curve structure are most important in determining fundamental parameters, and find, for example, that the second Fourier amplitude component of RR Lyrae light curves is even more important than period in determining the effective temperature of the star. We apply this analysis to observations of hundreds Cepheids in the Large Magellanic Cloud and thousands of RR Lyrae in the Magellanic Clouds and Galactic bulge to produce catalogues of estimated masses, radii, luminosities, and other parameters of these stars. As an example application, we estimate Wesenheit indices and use those to derive distance moduli to the Magellanic Clouds of μLMC,CEP = 18.688 ± 0.093, μLMC,RRL = 18.52 ± 0.14, and μSMC,RRL = 18.88 ± 0.17 mag.

A New Copyright- and Privacy-Protected Image Trading System Using a Novel SteganographyBased Visual Encryption Scheme

In copyright- and privacy-protected image trading systems, the image sent to the trusted third party (TTP) is visually encrypted, and the image is traditionally unrecognizable. The image, however, is suspicious and has possibility to be attacked. Image steganography then becomes more interesting than image encryption for this application, however, applying image steganography instead of image encryption degrades the fingerprint extraction performance. In addition, the CP is allowed to directly contact with the consumer in the conventional systems. Thus, the consumer’s privacy is not protected completely. This paper then proposes a new copyright- and privacy-protected image trading system with a novel steganography-based visual encryption scheme, where the scheme protects a commercial image much more securely by generating a recognizable image instead of a suspicious encrypted image. By replacing amplitude components of a dummy image by those of a commercial image, the output image looks like a degraded dummy image instead of the commercial image, while it contains some details of the commercial image, i.e., the amplitude components of the commercial image are hidden into a dummy cover image. A discrete cosine transform-based fingerprinting method, which is compatible with the proposed amplitude component replacing scheme, is also proposed in this paper to solve the problem of applying image steganography. As another contribution of this paper, the CP is not allowed to directly send the image reconstruction key to the consumer, for further consumer’s privacy protection. The second TTP is then introduced to the proposed system, and in addition, the image reconstruction key is encrypted by the CP before being sent to the consumer via the second TTP for more security. Experimental results show that the proposed scheme generates recognizable images and perfectly visually encrypts the commercial images. It also achieves much higher reconstructed image qualities than those of the conventional scheme, and the proposed system simultaneously enhances the fingerprinting performance using the proposed compatible fingerprinting method.

Studying of movement kinematics of dynamically active sieve

The article presents the movement kinematics of the modular bar element of a dynamically active polymer sieve of a vibrating screen. On the basis of analytical methods, the mathematical model was obtained, which makes it possible to determine the law and trajectory of the modular bar element movement depending on its geometric characteristics, physico-mechanical properties of the polymer material, the regime and technological parameters of the vibrating screen. The results of this research show that in the working frequency range of the vibrating screen grate, modular bar element of the dynamically active sieve moves along the trajectories, the envelope of which is represented by Cassini’s ovals, which along with the generation of the amplitude component in the horizontal and vertical directions allows one to obtain the selfcleaning effect of the sowing surface.

Bipedal Steps in the Development of Rhythmic Behavior in Humans

We contrast two related hypotheses of the evolution of dance: H1: Maternal bipedal walking influenced the fetal experience of sound and associated movement patterns; H2: The human transition to bipedal gait produced more isochronous/predictable locomotion sound resulting in early music-like behavior associated with the acoustic advantages conferred by moving bipedally in pace. The cadence of walking is around 120 beats per minute, similar to the tempo of dance and music. Human walking displays long-term constancies. Dyads often subconsciously synchronize steps. The major amplitude component of the step is a distinctly produced beat. Human locomotion influences, and interacts with, emotions, and passive listening to music activates brain motor areas. Across dance-genres the footwork is most often performed in time to the musical beat. Brain development is largely shaped by early sensory experience, with hearing developed from week 18 of gestation. Newborns reacts to sounds, melodies, and rhythmic poems to which they have been exposed in utero. If the sound and vibrations produced by footfalls of a walking mother are transmitted to the fetus in coordination with the cadence of the motion, a connection between isochronous sound and rhythmical movement may be developed. Rhythmical sounds of the human mother locomotion differ substantially from that of nonhuman primates, while the maternal heartbeat heard is likely to have a similar isochronous character across primates, suggesting a relatively more influential role of footfall in the development of rhythmic/musical abilities in humans. Associations of gait, music, and dance are numerous. The apparent absence of musical and rhythmic abilities in nonhuman primates, which display little bipedal locomotion, corroborates that bipedal gait may be linked to the development of rhythmic abilities in humans. Bipedal stimuli in utero may primarily boost the ontogenetic development. The acoustical advantage hypothesis proposes a mechanism in the phylogenetic development.

Development of a Multispectral Structured Illumination Reflectance Imaging (SIRI) System and Its Application to Bruise Detection of Apples

SIRI is a promising new imaging modality for enhancing quality detection of food. A liquid-crystal tunable filter (LCTF)-based multispectral SIRI system was developed and used for selecting optimal wavebands to detect bruising in apples. Immediately after impact bruising, ‘Delicious’, ‘Royal Gala’, ‘Granny Smith’, and ‘Golden Delicious’ apples were imaged by the system over the spectral region of 650 to 950 nm with 20 nm increments under sinusoidally modulated illumination at a spatial frequency of 100 cycles m-1. Each sample was subjected to two phase-shifted sinusoidal patterns of illumination with phase offsets of 0 and 2p/3 that were generated by a digital light projector. For comparison, spectral images were also captured under conventional uniform illumination. Spiral phase transform, a newly developed two-phase based demodulation method, was then used to retrieve amplitude component (AC) and direct component (DC) images from the SIRI images, from which ratio images were obtained by dividing the AC images by the DC images. It was found that the uniform illumination images failed to reveal the bruises in apples, whereas bruises were distinctly visible in the ratio images, with contrast varying with wavelength. Principal component analysis (PCA) showed that seven wavelengths from 710 to 830 nm were more relevant to bruise detection. A modified Otsu thresholding method based on the between-class variance was proposed for bruise segmentation from the ratio images at each of the seven wavelengths as well as the first principal component (PC1) images, which resulted in overall detection errors of 11.7% to 14.2%. This study has shown the potential of using a multispectral SIRI system for defect detection of fruit. Further research is needed to develop a general algorithm for defect detection of apples and upgrade the system toward real-time detection. Keywords: Defects, Detection, Fruit, Image analysis, LCTF, Structured illumination.

Resonant sloshing in an upright annular tank

Resonant sloshing in an upright annular tank is studied by using a new nonlinear modal theory, which is complete within the framework of the Narimanov–Moiseev asymptotics. The applicability is justified for a fairly deep liquid (the liquid-depth-to-outer-tank-radius ratio $1.5\lesssim h=\bar{h}/\bar{r}_{2}$) and away from the non-dimensional inner radii $r_{1}=\bar{r}_{1}/\bar{r}_{2}=0.08546$, 0.17618, 0.27826, 0.31323, 0.31855, 0.43444, 0.46015, 0.48434, 0.68655, 0.70118. The theory is used to describe steady-state (stable and unstable) resonant waves due to a harmonic excitation with the forcing frequency close to the lowest natural sloshing frequency. We show that the surge-sway-pitch-roll excitation is always of either longitudinal or elliptic type. Existing experimental results on the horizontally excited steady-state wave regimes in an upright circular tank ($r_{1}=0$) are utilised for validation. Inserting an inner pole with the radii $r_{1}\approx 0.25$ and 0.35 ($1.5\lesssim h$) causes that no stable swirling and/or irregular waves exist. The response curves for an elliptic-type excitation are examined versus the minor-axis forcing-amplitude component. Stable swirling is then expected being co- and counter-directed to the angular forcing direction. Passage to the rotary (circular) excitation keeps the co-directed swirling stable for all resonant forcing frequencies but the stable counter-directed swirling disappears.

Non-interferometric GB-SAR measurement: application to the Vallcebre landslide (eastern Pyrenees, Spain)

In the last decade, ground-based interferometry has proven to be a powerful technique for continuous deformation monitoring of landslides, glaciers, volcanoes, or manmade structures, among others. However, several limitations need to be addressed in order to improve the performances of the technique, especially for long-term monitoring. These limitations include the reduction of measurable points with an increase in the period of observation, the ambiguous nature of the phase measurements, and the influence of the atmospheric phase component. In this paper, a new procedure to process the amplitude component of ground-based synthetic aperture radar (GB-SAR) data acquired in discontinuous mode is compared and validated. The use of geometric features of the amplitude images combined with a matching technique will allow the estimation of the displacements over specific targets. Experimental results obtained during 19 months, in eight different campaigns carried out in the active landslide of Vallcebre (eastern Pyrenees, Spain), were analysed. During the observed period, from February 2010 to September 2011, displacements up to 80 cm were measured. The comparison with other surveying technique shows that the precision of the method is below 1 cm.