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Substrate‐borne vibrations are ubiquitous in nature and are used by diverse taxa to communicate and to obtain information about their environments. However, substrate‐borne vibrations remain understudied compared with other sensory and signaling modalities, in part due to human sensory biases. In addition, understanding and quantifying the transmission of vibrations remains a challenging task due to it being dependent on both signal properties and properties of the substrates that the signals transmit through. Here, we provide methods for playing back and measuring the transmission of vibrations throughout a substrate. Using linear resonant actuators, we conducted playbacks of pure tones and frequency sweeps on wooden dowels and on the stems of potted Ptelea trifoliata L. (Rutaceae) plants. We used scanning laser Doppler vibrometry to measure the signals at multiple locations along the length of the dowels and plant stems. We demonstrate that playback of a frequency sweep yields more data in a shorter amount of time than multiple playbacks and measurements of pure tone signals. Our results are also consistent with previous findings showing that signals produce frequency and location specific minima and maxima (nodes and antinodes) throughout the substrates, rather than simply attenuating with distance. This results in filtering of signals, such that their spectra are unique at any given measurement location—illustrating the importance of measuring vibrations at multiple locations. We discuss the implications of such filtering phenomena for vibrationally signaling animals and the biotremologists that study them. [ABSTRACT FROM AUTHOR]

The magneto-rheological elastomer is mostly used in vibration isolation, for which higher modulus and lower Payne effect factors are crucial parameters. Strain amplitudes and frequencies influence many applications under dynamic modes. In this work, the dynamic viscoelastic properties of MRE, fabricated using electrolyte iron (EI) particles, were measured for varying strain amplitude, magnetic field and frequency. A fractional Kelvin-Voigt (KV) model is used in a frequency region from 0.01 to 40 Hz to predict the rheological behaviour. However, the available models failed to explain the observed behaviour at low frequencies and high magnetic fields and increasing strain amplitude (i.e. in the non-viscoelastic region). Therefore, a new modified KV model is proposed in this work to incorporate the drawbacks and hence can validate for varying frequency, magnetic field and strain amplitudes. The added terms can also be used in the fractional derivative Maxwell model to explain the effect of strain amplitude and magnetic field at various frequencies. The proposed model significantly improves the quality of experimental prediction in the low-frequency range, corresponding to a slow dissipative process at different strain amplitudes. [ABSTRACT FROM AUTHOR]

Traditional vibro-acoustic modulation methods for bolt looseness detection often use a probe wave with single frequency. However, using a single frequency probe wave not only reduces the detection accuracy but also increases the difficulty of selecting the frequency of the probe wave. To overcome these drawbacks, this paper proposes a bolt looseness detection method based the vibro-acoustic modulation using a frequency sweep probe wave. For the low-frequency pump wave, the excitation frequency is set as the resonant frequency of the bolted joint to enhance the modulation effect. For the high-frequency probe wave, a frequency sweep excitation is used to replace the single frequency excitation, which improves the detection accuracy and overcomes the difficulty of selecting the probe frequency. A signal processing method is proposed to extract modulation information from the complex response signal obtained under a frequency sweep excitation. A nonlinear modulation index is defined using the extracted modulation information to quantify the loosening level of bolts. An experimental setup is designed to implement the vibro-acoustic modulation detection method on a bolted joint. Experimental results demonstrate that the proposed method is effective for detecting bolt looseness and has high detection sensitivity and accuracy for the early bolt loosening. [ABSTRACT FROM AUTHOR]

Nonlinear rheology of Pickering emulsions is used to further investigate the nonlinear and unrecoverable transformation of inner structures, which is beyond the linear viscoelastic regime of tiny structural disturbances. Exploring various rheological methods plays a vital role in emulsion applications, such as simulating the macroscopic structural transformation between static and liquidlike flow states, strain overshoot, and regeneration for broken structures. According to our previous studies, cellulose nanofibers (CNFs) Pickering emulsions are a typical system for investigating polymer-based emulsions with the auxiliary surfactant [didodecyldimethylammonium bromide (DDAB)] for enhancing CNF absorption. To further study different rheological properties by varying CNF or DDAB contents, multiple interval thixotropic test, large amplitude oscillatory shear, and concentration-time-dependent superposition are employed to study the linear viscoelasticity and structural transformation of nonlinear range. This research was conducted based on the previous published works [Cui et al., Materials 15, 8285 (2022)] as a further characterization for the same sample series. [ABSTRACT FROM AUTHOR]

Melanoma is one of the most severe cancers due to its great potential to form metastasis. Recent studies showed the importance of mechanical property assessment in metastasis formation which depends on the cytoskeleton dynamics and cell migration. Although cells are considered purely elastic, they are viscoelastic entities. Microrheology atomic force microscopy (AFM) enables the assessment of elasticity and viscous properties, which are relevant to cell behavior regulation. The current work compares the mechanical properties of human neonatal primary melanocytes (HNPMs) with two melanoma cell lines (WM793B and 1205LU cells), using microrheology AFM. Immunocytochemistry of F-actin filaments and phosphorylated focal adhesion kinase (p-FAK) and cell migration assays were performed to understand the differences found in microrheology AFM regarding the tumor cell lines tested. AFM revealed that HNPMs and tumor cell lines had distinct mechanical properties. HNPMs were softer, less viscous, presenting a higher power-law than melanoma cells. Immunostaining showed that metastatic 1205LU cells expressed more p-FAK than WM793B cells. Melanoma cell migration assays showed that WM73B did not close the gap, in contrast to 1205LU cells, which closed the gap at the end of 23 h. These data seem to corroborate the high migratory behavior of 1205LU cells. Microrheology AFM applied to HNPMs and melanoma cells allowed the quantification of elasticity, viscous properties, glassy phase, and power-law properties, which have an impact in cell migration and metastasis formation. AFM study is important since it can be used as a biomarker of the different stages of the disease in melanoma. [ABSTRACT FROM AUTHOR]

Common multi-frequency solution strategies for acoustic systems are either associated with high computational costs or resort to model reduction strategies, which potentially induce considerable approximation errors. In that context, this work proposes a fast multi-frequency solver for acoustic Boundary Element Method (BEM) analyses that combines conventional preconditioners with an accelerated recycling strategy, achieving in that way a fast and accurate iterative solution. Specifically, by approximating both the system and the related preconditioner by individual affine expressions, an upfront Galerkin projection on a global deflation basis is facilitated, therefore enabling the deployment of the accelerated recycling scheme. The latter acts by accelerating the construction of the related deflation projectors, therefore leading to a significantly faster recycling procedure. Finally, the efficiency of the global deflation basis is guaranteed through an Automatic Krylov subspaces Recycling for Deflation (AKR-D) [D. Panagiotopoulos, W. Desmet and E. Deckers, An accelerated subspaces recycling strategy for the deflation of parametric linear systems based on model order reduction, Comput. Methods Appl. Mech. Eng. 403 (2023) 115765] algorithm and thus, the cumulative number of iterations required by an iterative solver within a frequency sweep is drastically decreased. The proposed multi-frequency solver is tested on two industrially relevant examples of an interior and an exterior scattering problem, benchmarked against the traditional solution strategies. [ABSTRACT FROM AUTHOR]

Underwater electric potential (UEP) ship signatures are evaluated at a test site that provides only incoherent data from electric field sensors placed on the seabed. This paper shows how these data sets can be used to extract significant seabed parameters, which are evaluated by a numerical model combined with an optimization process in the frequency range from 1 Hz up to 100 kHz. This is in contrast to the controlled electromagnetic source technology used by geophysicists, which has to track both phase and amplitude, and, therefore, cannot simply be applied to data from per se stationary systems. Using the aforementioned frequency range within COMSOL Multiphysics (v6.0), the finite-element-based simulation software, a sensitivity analysis of seabed parameter behavior within a seabed depth range from 1 m to 20 m is evaluated for the highest sensitivity for each of the measurable field amplitudes of the locally available sensors. From this, the electrical conductivities of two seabed layers and the depth of the first layer can be extracted using a combination of a genetic algorithm and the Nelder–Mead method. In summary, phase information is not required to characterize the stratified seabed, providing a cost-effective approach to obtaining effective environmental conditions for free-water signature calculations. [ABSTRACT FROM AUTHOR]

Fourier domain mode locked (FDML) lasers are a class of frequency-swept lasers that are used to generate optical pulses with a wide sweep range, high repetition rate, and a low instantaneous bandwidth. They are commonly used in sensing and imaging applications, especially in optical coherence tomography. Ideally, the aspired features in the design of FDML lasers include a high coherence length, large sweep bandwidth, adjustable output power, and a high signal to noise ratio (SNR). However, the SNR of the output signal of FDML lasers is often lower than desired due to the presence of several irregularities in the output signal pattern, most notably because of the frequent occurrence of sharp power dips, also known as holes. These power dips originate due to the nonlinear gain dynamics of the semiconductor optical amplifier (SOA) that is employed in FDML lasers, while the occurrence frequency and strength of these dips are determined by the interaction of the FDML laser components, which involve the SOA, the tunable Fabry–Perot filter, and the optical delay fiber. Suppressing these power dips not only increases the output signal quality in terms of SNR, but also precludes the accumulation of phase offsets between subsequent roundtrips and facilitates convergence. As both current and future applications of FDML lasers are likely to require a higher signal power, in this paper, we are going to investigate the effect of self-phase modulation (SPM) in the optical fiber on dip formation and convergence. Since fiber nonlinearity, intracavity signal power, and fiber length all contribute to SPM, investigation of the effect of SPM on the formation of power-dips and operational convergence is critical. More importantly, the phase-mismatch that is caused by fiber-based SPM cannot be compensated easily in an FDML laser as in the case of chromatic dispersion, which necessitates a strategy for minimizing fiber-based SPM to ensure operational convergence and to secure a lower limit for the SNR of the output signal of FDML lasers. [ABSTRACT FROM AUTHOR]

BACKGROUND: Oleogels can be used in the food industry to reduce the consumption of solid fat in the human diet and diminish some of the industrial–technological issues of using oil instead of fat. Regarding the structural weakness of neat monoglyceride oleogel and the waxy mouthfeel of pure carnauba wax oleogel, as a result of the high melting and crystallization points, the present study aimed to diminish these defects. RESULTS: Carnauba wax (CBW) was used as a co‐gelator with distilled monoglyceride (DMG) at different weight ratios (100:0, 85:15, 70:30, 55:45, 40:60, and 0:100) (DMG: CBW) and two total gelator concentrations (50 and 100 g kg−1) to improve the DMG oleogel characteristics. The addition of CBW strengthened the DMG network and decreased the polymorphic transition. Thermal analysis showed just co‐crystallization at the 85:15 ratio, whereas, in the other combinations, high melting components of CBW crystalized at first. As a result of the crystal homogeneity and long‐time development, the oleogel properties improved at the 85:15 ratio. The low concentration of CBW and the formation of the eutectic system were efficient in the waxy mouthfeel reduction of oleogel at the 85:15 ratio in food applications. CONCLUSION: The DMG/CBW oleogel at the 85:15 ratio, with better structural and sensorial properties than DMG and CBW oleogels, respectively, has the potential for use instead of fat in food formulations. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The development and characterization of novel and natural environmental biopolymer gums for the food industries are essential due to consumers' growing desire to use synthetic-free ingredients in food products. This study aimed to characterize the Enzeroot gum (EG) obtained from Astragalus sarcocolla plant. EG contained carbohydrates (77.67%), uronic acid (12.34%), moisture (6.43%), and protein (1.18%). Fourier transform infrared spectroscopy confirmed EG as a typical polysaccharide. The mean molecular weight of the main portion of EG (87.49%) was 2.29 × 105 g/mol obtained by gel permeation chromatography. Thermogravimetric and derivative thermogravimetric analyses showed that the gum's weight loss occurred in three stages. Thermograms of differential scanning calorimetry depicted three endothermic phases. X-ray diffraction analysis confirmed amorphous behavior, also illustrated by scanning electron microscopy. EG dispersions (1 and 5%) displayed shear-thinning flow characteristics, described by the Herschel–Bulkley model. Frequency sweep measurements showed that the storage and loss modulus were frequency-dependent. EG indicated appropriate antioxidant and antimicrobial characteristics. In summary, the results of this study showed that EG biopolymer could be utilized as a thickener and stabilizer agent in the production of different food materials owing to its suitable functional properties. [ABSTRACT FROM AUTHOR]

The semi-solid Ca-gels were prepared from low-methoxyl pectins (methoxylation degree DM 4–36 %) of Oberna behen , Potamogeton natans, Tanacetum vulgare , Comarum palustre , Bergenia crassifolia , and Heracleum sosnowskyi. Pectins are characterized by Mw of 77–556 kDa and different content of HG and RG-I. The gels were prepared by addition of Ca2+ ions at varying stoichiometric ratios, R = 2 × [Ca2+]/[COO−], of 0.2–0.6, and a fixed pectin concentration of 10 g/L. It was shown that the presence of certain sets of structural characteristics in low-methoxyl pectins from different sources leads to the formation of gels with similar rheological properties. Pectins with Mw 77–98 kDa, DM 6–14 % form stiffer Ca-gels than pectins with Mw 218–253 kDa, DM 24–36 % at the same R. Pectins with Mw 346–556 kDa form the strongest Ca-gels. Their high Mw compensates for the influence of DM on the properties of Ca-gels. The stability of gels in PBS (pH 7.4) is determined mainly by proportion of 1,4-linked non-methoxylated GalA in pectins. Pectins with DM 4–14 % form more stable Ca-gels in PBS than pectins with DM 21–36 %. • Pectins with Mw ≥ 350 kDa can form Ca-gels at R 0.2. • Pectins (DM ≤ 14 %, 100 kDa) form stiffer Ca-gels than pectins (DM ≥ 20 %, 250 kDa). • Mw ≥ 350 kDa and low content of RG-I provide the highest stiffness of Ca-gels. • High Mw and low RG-I content provide the low recovery ability of Ca-gels. • Pectins with DM ≤ 14 % form Ca-gels stable in PBS. [ABSTRACT FROM AUTHOR]

The existing research on flight test risk control techniques related to flutter/ASE test is not systematic enough,and has limited consideration of civil fly-by-wire aircraft characteristic and onboard flight test engineer.The flutter/ASE flight test risk control technique is systematically studied,which includes the theoretical evaluation,test modification,flight test method,flight test risk analysis,risk mitigation measures and emergency procedures formulation. Aiming at three identified hazards including flutter/ASE instability,adverse handling quality and local structure damage,a new technique is proposed for onboard flight test engineers to cutoff the excitation when the vibration limit is exceeded or abnormal. The dedicated ground monitor software is developed to perform the margin quantitative analysis of flutter/ASE in real time. The technique is applied to a certain model flight test for flutter/ASE flight test verification. The results show that the risk control technique can reduce the flight test risk and cost effectively,the manual cutoff technique can stop the excitation within 1 second to protect the aircraft structure safety,and the real-time analysis technique can calculate the stability margin quickly and improve the flight test efficiency.

NMR spectra acquired with experiments using frequency-sweeps such as the wide-band uniform-rate smooth truncation (WURST) spin-echo and Carr-Purcell-Meiboom-Gill (CPMG) sequences cannot be absorptively phased by using only conventional zeroth- and first-order phase correction. Implementation of phase correction up to the second-order is described for obtaining absorptive spectra, which have more desirable line shapes and noise properties than magnitude spectra. The relationship of the second-order phase to the parameters of frequency sweeps is derived. The second-order phasing in the frequency-domain is equivalent to a point spread in the time-domain signal. The application of second-order phase correction is demonstrated with a wideline 35Cl CPMG spikelet spectrum.

Simple Summary: Colorectal cancer (CRC) is presently the third-most abundant and the second-most lethal cancer worldwide. Thus, there is a real and urgent need to investigate the processes behind the appearance, development, and proliferation of CRC cells. Several biochemical pathways have been investigated to understand their role in oncogene activation and tumor-suppressor gene inhibition. Despite the research increase in biochemistry, there is still a need to better understand the biophysical cues that drive the activation of signaling pathways relevant to mechanotransduction and cell transformation. The elucidation of these biological processes may help to hinder oncogenic mechanisms and to find biomarkers that could be used to design more personalized therapeutic strategies. Colorectal cancer (CRC) has been addressed in the framework of molecular, cellular biology, and biochemical traits. A new approach to studying CRC is focused on the relationship between biochemical pathways and biophysical cues, which may contribute to disease understanding and therapy development. Herein, we investigated the mechanical properties of CRC cells, namely, HCT116, HCT15, and SW620, using static and dynamic methodologies by atomic force microscopy (AFM). The static method quantifies Young's modulus; the dynamic method allows the determination of elasticity, viscosity, and fluidity. AFM results were correlated with confocal laser scanning microscopy and cell migration assay data. The SW620 metastatic cells presented the highest Young's and storage moduli, with a defined cortical actin ring with distributed F-actin filaments, scarce vinculin expression, abundant total focal adhesions (FAK), and no filopodia formation, which could explain the lessened migratory behavior. In contrast, HCT15 cells presented lower Young's and storage moduli, high cortical tubulin, less cortical F-actin and less FAK, and more filopodia formation, probably explaining the higher migratory behavior. HCT116 cells presented Young's and storage moduli values in between the other cell lines, high cortical F-actin expression, intermediate levels of total FAK, and abundant filopodia formation, possibly explaining the highest migratory behavior. [ABSTRACT FROM AUTHOR]

Underwater electric potential (UEP) ship signatures are evaluated at a test site that provides only incoherent data from electric field sensors placed on the seabed. This paper shows how these data sets can be used to extract significant seabed parameters, which are evaluated by a numerical model combined with an optimization process in the frequency range from 1 Hz up to 100 kHz. This is in contrast to the controlled electromagnetic source technology used by geophysicists, which has to track both phase and amplitude, and, therefore, cannot simply be applied to data from per se stationary systems. Using the aforementioned frequency range within COMSOL Multiphysics (v6.0), the finite-element-based simulation software, a sensitivity analysis of seabed parameter behavior within a seabed depth range from 1 m to 20 m is evaluated for the highest sensitivity for each of the measurable field amplitudes of the locally available sensors. From this, the electrical conductivities of two seabed layers and the depth of the first layer can be extracted using a combination of a genetic algorithm and the Nelder–Mead method. In summary, phase information is not required to characterize the stratified seabed, providing a cost-effective approach to obtaining effective environmental conditions for free-water signature calculations.

Tuned-mass-dampers are extensively used in physical systems in order to reduce the dynamic response of the primary structures. The damping in a tuned-mass-damper system plays a significant role. In many engineering systems, we see damping is hysteretic in nature. Tuned-mass systems with nonlinear hysteretic damping are mathematically challenging. In this paper, tuned mass systems with rate-independent hysteresis are studied. In particular, first we study tuned mass systems with the famous Bouc-Wen model, and then we study tuned mass systems with the Bouc-Wen model and a recently developed scalar hysteresis model in parallel. Numerical approaches are used to study the dynamic responses of the systems. The sine sweep responses show two resonance peaks. The sine sweep responses indicate the amplitude versus frequency of the systems. The numerical results obtained for two different hysteretic dampers are compared. [ABSTRACT FROM AUTHOR]

In the present study binary formulations of sodium hyaluronate (▪) and hypromellose (▪) were proposed as medical devices in the field of eye surgeries. Viscoelasticity is tested directly on binary solutions while the rheological behavior in the human eye is mimicked by monitoring the viscoelasticity of ternary mixtures ▪/▪/▪. Both binary and ternary formulations were rheologically characterized at 25 ∘C and 37 ∘C by means of measurements in the oscillatory regime. Amplitude sweep tests revealed that the range of linear viscoelasticity is strongly dependent on the concentration of ▪. For the proposed formulations, it was ascertained that the cohesive energy density at 37 ∘C decreases as ▪ concentration surges; in contrast, at 25 ∘C we detected an increase of cohesive energy were detected. At ▪ mass fraction of α 1 , the two obtained values were comparable. Frequency sweep tests revealed the pseudoplastic character of the binary formulations. In order to fit the complex viscosity modules, the Carreau-Yasuda model was modified. Numerical analysis of the results indicates that the best-fit to the model is obtained when the characteristic parameters take constant values, i.e. n = 0 and m = 1 , regardless of the composition of the formulation. This implies that the modulus of complex viscosity decays hyperbolically. Frequency sweep tests on the ternary formulations were analyzed in terms of both the modulus of complex viscosity to confirm the previous scientific evidence together with an investigation of the phase shift angle between the viscous and elastic components. The results indicate that the addition of water has a different impact on the structure and the cohesion of the mixture at different temperatures. These results suggest that the ternary mixture structure can be sensitively modulated by temperature and the content of water. • The network of Sodium Hyaluronate/Hypromellose is probed by cohesive energy density. • Intraocular medical devices properties are tuned by viscoelastic formulations. • Revised Carreau-Yasuda may assist ophthalmic surgeries predicting complex viscosity. [ABSTRACT FROM AUTHOR]

An adaptive interpolation scheme is proposed to accurately calculate the wideband responses in electromagnetic simulations. In the proposed scheme, the sampling points are first carefully divided into several groups based on their responses to avoid the Runge phenomenon and the error fluctuations, and then different interpolation strategies are used to calculate the responses in the whole frequency band. If the relative error does not satisfy the predefined threshold in a specific frequency band, it will be refined until the error criterion is met. The detailed error analysis is also presented to verify the accuracy of the interpolation scheme. At last, three numerical examples are carried out to validate its accuracy and efficiency. [ABSTRACT FROM AUTHOR]

In the current study, the nanofiber gel of tomato pomace was prepared using a super disk grinder device available at Nano Novin Polymer Co., Iran. Three different concentrations (2, 4 and 6%) of the gel prepared and rheological tests including amplitude sweep, frequency sweep, temperature sweep, and flow behavior were done. DLS results showed that the average diameter of tomato nano-gel was around 38 nm. The power law model was chosen as the best model for describing flow behavior data. All samples showed a shear-thinning behavior that viscosity decreased with increasing shear rate. A hysteresis loop was observed in all samples which confirmed the thixotropic characteristic of gels. Based on amplitude sweep data, elastic modulus (G') was higher than viscous modulus (G"), in addition, crossover points of all gels showed that the flowability decreased with increasing concentrations. Based on frequency data, G' in all concentrations was higher than G" and both parameters increased with increasing concentration from 2 to 6%. In lower frequencies, all gels showed solid-like behavior while G' and G" increased with increasing frequency indicating the weakening of the gel network. G' and G" gradually decreased with increasing temperature from 5 to 50 ºC which confirmed that all gels were weakened at high temperatures, but in the cooling cycle, all gels recovered their structures and no remarkable hysteresis was observed.

As a result of increasing variability of network impedance, interest in impedance estimation techniques is growing. This review contextualises local impedance estimation techniques by providing a historical prospective on the uses of these techniques, from the early implementations designed to monitor power quality to the latest techniques integrated into converters designed to update the controller with the most recent network information. This is followed by clear and consolidated descriptions, a complete classification and comparison tables of local estimation techniques intended to assist engineers and researchers choose an estimation technique that is suitable to their application. The discussed techniques are then ranked for a range of application priorities such as accuracy, least disruptive to the network, most suitable for wide frequency spectrum estimations and rapidity of estimation. Practical applications of impedance estimation are discussed, such as network characterisation, anti-islanding detection, filter resonance avoidance and controller tuning. To conclude the review, future trends are identified.

Use of sweeping mode with a 3.6 MHz High Intensity Focused Ultrasound (HIFU) allows cavitation activity to be controlled. This is especially true in the pre-focal zone where the high concentration of bubbles acts as an acoustic reflector and quenches cavitation above this area. Previous studies attributed the enhancement of cavitation activity under negative sweep to the activation of more bubble nuclei, requiring deeper investigations. After mapping this activity with SCL measurements, cavitation noise spectra were recorded. The behavior of the acoustic broadband noise follows the sonochemical one i.e., showing the same attenuation (positive scan) or intensification (negative scan) of cavitational activity. In 1 M NaCl 3.7 mM 2-propanol solution saturated by a mixture of Ar-15.5%O2-2.2%N2, intensities of SL spectra are high enough to allow detection of several molecular emissions (OH, NH, C2, Na) under negative frequency sweeps. This is the first report of molecular emissions at such high frequency. Their intensities are low, and they are very broad, following the trend obtained at fixed frequency up to 1 MHz. Under optimized conditions, CN emission chosen as a spectroscopic probe is strong enough to be simulated, which is reported for the first time at such high frequency. The resulting characteristics of the plasma do not show any spectral difference, so bubble nature is the same in the pre-and post-focal zone under different sweeping parameters. Consequently, SL and SCL intensification was not related to a change in plasma nature inside the bubbles but to the number of cavitation bubbles.

• Brain–behavior relationships probed with oddball and frequency-sweep paradigms. • Convergent behavioral and neural measures at group and individual levels. • Face individuation minimum at 50 ms and optimum at 170 ms stimulus duration. • Large inter-individual differences in neural and behavioral responses at mid-rates. • Neural peak latency at ~185 ms predicted individuals' behavioral accuracy. Establishing consistent relationships between neural activity and behavior is a challenge in human cognitive neuroscience research. We addressed this issue using variable time constraints in an oddball frequency-sweep design for visual discrimination of complex images (face exemplars). Sixteen participants viewed sequences of ascending presentation durations, from 25 to 333 ms (40–3 Hz stimulation rate) while their electroencephalogram (EEG) was recorded. Throughout each sequence, the same unfamiliar face picture was repeated with variable size and luminance changes while different unfamiliar facial identities appeared every 1 s (1 Hz). A neural face individuation response, tagged at 1 Hz and its unique harmonics, emerged over the occipito-temporal cortex at 50 ms stimulus duration (25–100 ms across individuals), with an optimal response reached at 170 ms stimulus duration. In a subsequent experiment, identity changes appeared non-periodically within fixed-frequency sequences while the same participants performed an explicit face individuation task. The behavioral face individuation response also emerged at 50 ms presentation time, and behavioral accuracy correlated with individual participants' neural response amplitude in a weighted middle stimulus duration range (50–125 ms). Moreover, the latency of the neural response peaking between 180 and 200 ms correlated strongly with individuals' behavioral accuracy in this middle duration range, as measured independently. These observations point to the minimal (50 ms) and optimal (170 ms) stimulus durations for human face individuation and provide novel evidence that inter-individual differences in the magnitude and latency of early, high-level neural responses are predictive of behavioral differences in performance at this function. [ABSTRACT FROM AUTHOR]

This study describes the viscoelastic characterizations of unmodified and heat-modified mangrove particle (MP)-filled high-density polyethylene (HDPE) composites. The untreated (unmodified) and treated (modified) MPs were compounded with HDPE matrix at 10, 20 and 30 wt% in a twin-screw extruder and compression moulded into thin sheets for rheological characterizations (amplitude and frequency sweeps). The amplitude sweeps of the dynamic rheological analysis indicated that 20 wt% treated composite has the highest linear viscoelastic region of 0.1% with the highest storage and loss modulus of 1310 and 150 kPa, respectively. The frequency sweep showed an increase in storage and loss moduli as particle loading increased. The zero shear viscosities of pure HDPE were nearly 3990 Pa·s, while the MP-reinforced HDPE composites were ≥185,440 Pa·s with treated composites exhibiting higher values. [ABSTRACT FROM AUTHOR]

The geotechnical and geodynamic characteristics of railway earthworks under train loading are important quantities for railway and geotechnical engineers, but difficult to quantify. Characterizing the anticipated settlement and dynamic properties of compacted fills after earthwork construction, but before track laying, is advantageous, because modifying construction after laying the track is significantly more expensive. The difficulty in measuring these indices arises from the need to perform cyclic loading that realistically simulates the frequencies and magnitudes induced by trains. To address this issue, this paper introduces a novel shaker designed to apply cyclic loads similar to those of trains. The paper first presents an outline of the design requirements for the shaker, followed by the development of a theoretical dynamics model to aid mechanical design. This model is used for examining various shaker configurations, especially their performance under different potential testing conditions. The shaker's final design includes dual eccentric rotors that excite an adjustable-mass counterweight, complemented by a lateral support frame to counter horizontal movement and ensure vertical excitation. Once the shaker is built, it is used to evaluate newly constructed mudstone earthworks near a railway line. A method for estimating the dynamic stiffness and damping of earthworks is proposed, which uses data from frequency sweep test data from the shaker. Outputs from the dynamics model show close alignment with the field results. Finally, a method for designing the shaker configuration according to the desired loads is proposed. • Large-scale shaker developed for earthworks testing; replicates train-induced stress. • Novel dual-rotor design enhances economic efficiency; no cooling system needed. • Shaker effective in estimating earthworks stiffness and damping coefficients. • Synchronization issues in rotors identified; stable output between 6 and 16 Hz. • Field tests confirm model accuracy; suitable for railway earthworks evaluation. [ABSTRACT FROM AUTHOR]

Most industrial process lines involve mixing complex dispersions, which can include non‐Newtonian liquids and viscoelastic particles. Knowledge of the parameters of these components may provide a key for understanding how dispersions are formed and how equipment should be designed. One parameter is the shear modulus, which describes the ability of particles to resist mechanical stresses. This parameter may play the main role in the mixing process, when a dispersion is formed by the mechanical influence of a rotor (slice or shear in a rotor‐stator mixer). In this work, two methods were chosen for measuring the shear modulus: the evaluation method, based on the Warner‐Bratzler cut test, and the oscillatory method. Both methods were used for measuring viscoelastic clusters of particles, and the results were adjusted for the purposes of the comparison. The comparison shows that the shear modulus values obtained from Warner‐Bratzler are higher than the values obtained from the oscillatory test for the same conditions. This difference can be explained by differences in the mechanical processes during the experiments. [ABSTRACT FROM AUTHOR]

Background: Metaconcrete is a new concept of concrete, showing marked attenuation properties under impact and blast loading, where traditional aggregates are partially replaced by resonant bi-material inclusions. In a departure from conventional mechanical metamaterials, the inclusions are dispersed randomly as cast in the material. The behavior of metaconcrete at supersonic frequencies has been investigated theoretically and numerically and confirmed experimentally. Objective: The feasibility of metaconcrete to achieve wave attenuation at low frequencies demands further experimental validation. The present study is directed at characterizing dynamically, in the range of the low sonic frequencies, the—possibly synergistic—effect of combinations of different types of inclusions on the attenuation properties of metaconcrete. Methods: Dynamic tests are conducted on cylindrical metaconcrete specimens cast with two types of spherical inclusions, made of a steel core and a polymeric coating. The two inclusions differ in terms of size and coating material: type 1 inclusions are 22 mm diameter with 1.35 mm PDMS coating; type 2 inclusions are 24 mm diameter with 2 mm layer natural rubber coating. Linear frequency sweeps in the low sonic range (< 10 kHz), tuned to numerically estimated inclusion eigenfrequencies, are applied to the specimens through a mechanical actuator. The transmitted waves are recorded by transducers and Fast-Fourier transformed (FFT) to bring the attenuation spectrum of the material into full display. Results: Amplitude reductions of transmitted signals are markedly visible for any metaconcrete specimens in the range of the inclusion resonant frequencies, namely, 3,400-3,500 Hz for the PDMS coating inclusions and near 3,200 Hz for the natural rubber coating inclusions. Specimens with mixed inclusions provide a rather uniform attenuation in a limited range of frequencies, independently of the inclusion density, while specimens with a single inclusion type are effective over larger frequency ranges. With respect to conventional concrete, metaconcrete reduces up to 90% the amplitude of the transmitted signal within the attenuation bands. Conclusions: Relative to conventional concrete, metaconcrete strongly attenuates waves over frequency bands determined by the resonant frequencies of the inclusions. The present dynamical tests conducted in the sonic range of frequencies quantify the attenuation properties of the metaconcrete cast with two types inclusions, providing location, range and intensity of the attenuation bands, which are dependent on the physical-geometric features of the inclusions. [ABSTRACT FROM AUTHOR]

Chinese lexical tones determine word meaning and are crucial in reading development. Reduced tone awareness is widely reported in children with reading difficulties (RD). Lexical-tone processing requires sensitivity to frequency-modulated sound changes. The present study investigates whether reduced tone awareness in children with RD is reflected in basic auditory processing and the level at which the breakdown occurs. Magnetoencephalographic techniques and an oddball paradigm were used to elicit auditory-related neural responses. Five frequency sweep conditions were established to mirror the frequency fluctuation in Chinese lexical tones, including one standard (level) sweep and four deviant sweeps (fast-up, fast-down, slow-up, and slow-down). A total of 14 Chinese-speaking children aged 9–12 years with RD and 13 age-matched typically developing children were recruited. The participants completed a magnetoencephalographic data acquisition session, during which they watched a silent cartoon and the auditory stimuli were presented in a pseudorandomized order. The results revealed that the significant between-group difference was caused by differences in the level of auditory sensory processing, reflected by the P1m component elicited by the slow-up frequency sweep. This finding indicated that auditory sensory processing was affected by both the duration and the direction of a frequency sweep. Sensitivity to changes in duration and frequency is crucial for the processing of suprasegmental features. Therefore, this sensory deficit might be associated with difficulties discriminating two tones with an upward frequency contour in Chinese.

The ability to rapidly encode the direction of frequency contour contained in frequency-modulated (FM) sweeps is essential for speech processing, music appreciation, and conspecific communications. Psychophysical evidence points to a common temporal window threshold for human listeners in processing rapid changes in frequency glides. No neural evidence has been provided for the existence of a cortical temporal window threshold underlying the encoding of rapid transitions in frequency glides. The present magnetoencephalography study used the cortical mismatch negativity activity (MMNm) to investigate the minimum temporal window required for detecting different magnitudes of directional changes in frequency-modulated sweeps. A deviant oddball paradigm was used in which directional upward or downward frequency sweep serves as the standard and the same type of sweep with the opposite direction serves as its deviant. Stimuli consisted of unidirectional linear frequency-sweep complexes that swept across speech-relevant frequency bands in durations of 10, 20, 40, 80, 160, and 320 ms (with corresponding rates of 50, 25, 12.5, 6.2, 3.1, 1.5 oct/s). The data revealed significant magnetic mismatch field responses across all sweep durations, with slower-rate sweeps eliciting larger MMNm responses. A greater temporally related enhancement in MMNm response was obtained for rising but not falling frequency sweep contours. A hemispheric asymmetry in the MMNm response pattern was observed corresponding to the directionality of frequency sweeps. Contrary to psychophysical findings, we report a temporal window as short as 10 ms sufficient to elicit a robust MMNm response to a directional change in speech-relevant frequency contours. The results suggest that auditory cortex requires extremely brief temporal window to implicitly differentiate a dynamic change in frequency of linguistically relevant pitch contours. That the brain is extremely sensitive to fine spectral changes contained in speech-relevant glides provides cortical evidence for the ecological importance of FM sweeps in speech processing.

β_glucan is dietry fibre and water soluble hydrocolloid (gum). It has various physical properties such as thickening, stabilizing, emulsification, and gelation. in this study the effect of intensity and time at four different powers (0, 200, 300, 400 w) in three time (0, 3.5 and 7 min) intrevals were investigated on the physicochemical and the rheological properties of extracted.ß_glucan. The results showed that ultrasound intensity and time were significant on ash, protein, fibre, carbohydrate and β-glucan content (p < 0.05), While it was not significant on fats (p > 0.05). The highest amount of β-glucan (77.1%) was observed at power 200 w for 3.5 minutes, also the lowest amount of ß-glucan (55.6%) was observed at power 400 w for 3.5 minutes. Result showed that apparent viscosity decreased by increasing of the shear rate. All samples showed shear thinning behavior. The highest consistency coefficient, zero shear viscosity and lowest flow index was control sample., and the lowest consistency coefficient and zero shear viscosity and the highest flow index was observed at power 400 w for 3.5 minutes. The results of fitting data using different rheological models showed Herschel and Carreau models have maximum R². Linear region assign about 0.5 % using strain sweep test. Result of frequency sweep test showed initially, loss and storage modulus were increased by adding frequency, the storage modulus were reduced at high frequencies and in all samples were G″ > G′. [ABSTRACT FROM AUTHOR]

This study presents the results of laboratory experiments and analyses carried out to evaluate the rheological performance of nanoclay (NC) modified asphalt binders from 10°C to 70°C. A viscosity graded binder, VG-30, was modified using 2%, 4%, and 6% NC by weight of the base binder. The suitability of the NC modification was ascertained using a series of rheological evaluations, including a frequency sweep test (10°C–70°C), linear amplitude sweep (LAS) test (10°C, 20°C, and 30°C), and multiple stress creep and recovery (MSCR) test (40°C, 50°C, 60°C, and 70°C). Scanning electron microscopy (SEM) was carried out on the unmodified and modified asphalt binders to assess the microscopic dispersion of NC in the base asphalt binder. The SEM images demonstrated that with an increase in the percentage of NC, the physical dispersion of the modifier in the base asphalt binder changes. Six percent of the NC was found to form an interlocked phase within the composite asphalt binder matrix. It was found that the h -parameter obtained from Cole-Cole plots at individual temperatures offers a better and clearer comparison between the asphalt binders in comparison to the master curves and combined Cole-Cole plots. The analysis using h -parameter indicated a higher elasticity and lower temperature susceptibility offered by the NC modified binders. With an increase in the percentage of nanoclay, both the fatigue and rutting performance improved. The value of the Jnr decreased while the value of the percentage recovery (R) increased with an increase in the percentage of the NC. At the temperature of 70°C, only a 6% NC modified asphalt binder was found to be suitable for standard traffic conditions. The LAS test resulted in a higher value of A and an insignificant increase in the value of B for NC modified binders in comparison to the values obtained for VG-30. No specific trend was observed in the value of A at different CSRs, and it suggested from this study that an average value may be used. The number of cycles to failure for NC modified binders was found to be higher than VG-30. A statistical analysis carried out for different parameters revealed that the NC modification has a significant effect on the performance parameters of asphalt binders at all the test temperatures. A simple framework for the cost-benefit analysis has been proposed in this study, which revealed a 6% NC modification to be the optimum dosage for attaining a higher benefit in comparison to the cost. [ABSTRACT FROM AUTHOR]

Large quantities of waste toner (WT) are generated annually either due to the incessant manufacturing process or from copying machines. Disposal of WT is primarily in landfills, which deteriorates the environment. This study attempts to overcome this predicament by utilizing WT for asphalt pavement construction by means of incorporating it in asphalt binder. The effect of WT on rheological properties of asphalt binder was explored in this research. An unmodified asphalt binder AC30 was adopted and modified with three contents of WT (7%, 14%, and 21% by weight). Tests including high-temperature performance grade (PG), temperature sweep, frequency sweep, and multiple stress creep and recovery (MSCR) were performed in this study. Mixing and compaction temperature was observed to marginally increase on introduction of WT. The addition of WT was perceived to cause a bump in high-temperature PG of AC30 binder. Improvement in rutting resistivity of AC30 binder was recorded. However, a degradation of fatigue resistance was observed. Master curves indicated an enhancement in complex shear modulus (|G*|) and reduction in phase angle (δ) at low frequencies due to incorporation of WT. However, at higher frequencies, convergence of the curves was observed. MSCR analysis indicated that WT addition enhanced percent recovery (R) and decreased nonrecoverable creep compliance (Jnr). Overall, the addition of WT was observed to cause changes in the rheological behavior of AC30 binder and an improved resistance to rutting at high temperature. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive analysis of blended asphalt binders extracted from mixtures that contain various amounts of reclaimed asphalt pavements (RAP). The analysis is performed within a thermodynamically consistent non-linear viscoelastic (NVE) modeling framework, which has the advantage of accounting for the contributions of each of the constituents (i.e. virgin binder and RAP binder) to the response of the blended binder. In order to calibrate and validate the NVE model, the RAP blended binders were subjected to different testing protocols: frequency sweep, multiple stress creep and recovery, repeated creep and recovery with multiple stress levels, random creep and recovery, and stress relaxation. For the binders used in this study, linear viscoelasticity (LVE) was suitable to model the frequency sweep and multiple stress creep and recovery data, but it did not capture the repeated creep and recovery with multiple stress levels results that involved higher stress and strain levels. The NVE model, on the other hand, was successful in describing the repeated creep and recovery with multiple stress levels results. The validation was achieved by comparing the NVE model predictions with the random creep and recovery and stress relaxation test results. Finally, the paper recommends a new method, based on the parameters of the NVE model, to evaluate the rutting resistance of blended asphalt binders. [ABSTRACT FROM AUTHOR]

Chinese lexical tones determine word meaning and are crucial in reading development. Reduced tone awareness is widely reported in children with reading difficulties (RD). Lexical-tone processing requires sensitivity to frequency-modulated sound changes. The present study investigates whether reduced tone awareness in children with RD is reflected in basic auditory processing and the level at which the breakdown occurs. Magnetoencephalographic techniques and an oddball paradigm were used to elicit auditory-related neural responses. Five frequency sweep conditions were established to mirror the frequency fluctuation in Chinese lexical tones, including one standard (level) sweep and four deviant sweeps (fast-up, fast-down, slow-up, and slow-down). A total of 14 Chinese-speaking children aged 9–12 years with RD and 13 age-matched typically developing children were recruited. The participants completed a magnetoencephalographic data acquisition session, during which they watched a silent cartoon and the auditory stimuli were presented in a pseudorandomized order. The results revealed that the significant between-group difference was caused by differences in the level of auditory sensory processing, reflected by the P1m component elicited by the slow-up frequency sweep. This finding indicated that auditory sensory processing was affected by both the duration and the direction of a frequency sweep. Sensitivity to changes in duration and frequency is crucial for the processing of suprasegmental features. Therefore, this sensory deficit might be associated with difficulties discriminating two tones with an upward frequency contour in Chinese. [ABSTRACT FROM AUTHOR]

In this letter, we present a novel and efficient broadband spectral numerical Green's function (S-NGF) for inhomogeneous region. The proposed S-NGF is formulated in terms of the matrices that are obtained by the finite-element method (FEM). By performing modal analysis to FEM matrices, the proposed S-NGF is encapsulated by a series of resonant solenoidal modes where the operating frequency is embedded in the expansion coefficients. Besides, the convergence of the series of resonant solenoidal modes can be greatly accelerated by performing an extraction at one low wavenumber. The S-NGF can be rapidly reconstructed at different frequencies when it is integrated into the surface integral equation for inhomogeneous object modeling. The proposed algorithm is easy to implement, and well suited for the design and optimization of inhomogeneous electromagnetic structures, where fast solutions at massive frequencies are called for. The numerical examples demonstrate the efficiency and accuracy of the proposed scheme. [ABSTRACT FROM AUTHOR]

In the current study, the nanofiber gel of tomato pomace was prepared using a super disk grinder device available at Nano Novin Polymer Co., Iran. Three different concentrations (2, 4 and 6%) of the gel prepared and rheological tests including amplitude sweep, frequency sweep, temperature sweep, and flow behavior were done. DLS results showed that the average diameter of tomato nano-gel was around 38 nm. The power law model was chosen as the best model for describing flow behavior data. All samples showed a shear-thinning behavior that viscosity decreased with increasing shear rate. A hysteresis loop was observed in all samples which confirmed the thixotropic characteristic of gels. Based on amplitude sweep data, elastic modulus (G') was higher than viscous modulus (G"), in addition, crossover points of all gels showed that the flowability decreased with increasing concentrations. Based on frequency data, G' in all concentrations was higher than G" and both parameters increased with increasing concentration from 2 to 6%. In lower frequencies, all gels showed solid-like behavior while G' and G" increased with increasing frequency indicating the weakening of the gel network. G' and G" gradually decreased with increasing temperature from 5 to 50 ºC which confirmed that all gels were weakened at high temperatures, but in the cooling cycle, all gels recovered their structures and no remarkable hysteresis was observed. [ABSTRACT FROM AUTHOR]

The fortification of the processed cheese (PC) with bioactive compounds can increase their benefits for the health and also consumer acceptance. In the present study, rheological, chemical and sensory characteristics of the processed cheese containing different quantities of tomato powder (0%, 1%, 2% and 4% wt/wt) with the appropriate levels of bioactive components were evaluated during 90 days of storage. The results showed that the PC samples containing tomato powder (PCTs) had higher levels of proteolysis extent, phenolic and lycopene contents and antioxidant activity. However, the PCTs had lower levels of pH and lipolysis indexes. Generally, lycopene and phenolic contents and antioxidant activity decreased and pH, proteolysis and lipolysis index increased during storage. The results obtained from the frequency sweep test and temperature sweep test, indicated that, the samples had solid-type structure and tomato powder decreased the solid like behavior of the PC (G′ > G″). Sensory analysis showed that the processed cheese with the average level of tomato powder (2%) had maximum scores of flavor, color and total acceptance and also the PCTs were significantly (P < 0.05) less rigid and more spreadable than the control PC and these findings were according to the achievements obtained by dynamic oscillation rheometry. Finally overall results indicated that tomato powder could be helpful for the manufacturing of new product with different functional and sensory specifications. [ABSTRACT FROM AUTHOR]

The working temperature of a bituminous pavement can typically range from 75 ∘ C to − 20 ∘ C. Bitumen shows a wide spectrum of mechanical behaviour in this temperature range and these include those of a viscoelastic fluid, a viscoelastic solid and an elastic solid. Due to the amorphous nature of the material, the transitions between such mechanical responses are gradual. This investigation focuses on the transition between the viscoelastic solid and the viscoelastic fluid state of a wide class of bitumens with regard to unaged and short-term aged conditions. An unmodified binder and three modified binders were subjected to temperature sweep and frequency sweep in the viscoelastic regime across a wide range of temperatures. Depending on the material and the post-processing method followed, one could discern a viscoelastic fluid and a viscoelastic solid regime and a frequency-dependent mixture regime consisting of a viscoelastic solid and a viscoelastic fluid, across the tested temperatures and frequencies. It is shown in this investigation that parameters such as G ′ –G ′′ crossover and frequency independence of tan δ cannot be used to estimate the temperatures corresponding to the onset of either fluid-like or solid-like behaviour of the body as the temperature varies. It is also shown that the time–temperature superposition principle does not hold good in the temperature regime tested (75–25 ∘ C) due to the viscoelastic transitions exhibited by bitumen and modified bitumen. [ABSTRACT FROM AUTHOR]

A method for calculating the frequency sweep law of a vibration source is proposed and substantiated, which yields a flat spectrum of the correlogram of the target wave, regardless of natural amplitude–frequency distortions introduced by the medium and source. Such a spectrum serves as the main prerequisite for achieving maximum resolution of closely spaced wave pulses in the resulting seismogram. The methodology includes test sounding of a typical seismic geological object with any linear sweep signal in the desired frequency range, separation and spectral analysis of the vibrogram of the target wave, splitting of the resulting spectrum into many narrow frequency intervals, and calculating for each of the intervals its own partial linear sweep. Construction of a continuous sequence of these partial sweeps is the final operation in synthesizing an adaptive nonlinear (piecewise linear) sweep signal. In this study, the necessary conditions are found and formulated that ensure correctness of the coupling procedure for partial sweeps. [ABSTRACT FROM AUTHOR]

The ability to rapidly encode the direction of frequency contour contained in frequency-modulated (FM) sweeps is essential for speech processing, music appreciation, and conspecific communications. Psychophysical evidence points to a common temporal window threshold for human listeners in processing rapid changes in frequency glides. No neural evidence has been provided for the existence of a cortical temporal window threshold underlying the encoding of rapid transitions in frequency glides. The present magnetoencephalography study used the cortical mismatch negativity activity (MMNm) to investigate the minimum temporal window required for detecting different magnitudes of directional changes in frequency-modulated sweeps. A deviant oddball paradigm was used in which directional upward or downward frequency sweep serves as the standard and the same type of sweep with the opposite direction serves as its deviant. Stimuli consisted of unidirectional linear frequency-sweep complexes that swept across speech-relevant frequency bands in durations of 10, 20, 40, 80, 160, and 320 ms (with corresponding rates of 50, 25, 12.5, 6.2, 3.1, 1.5 oct/s). The data revealed significant magnetic mismatch field responses across all sweep durations, with slower-rate sweeps eliciting larger MMNm responses. A greater temporally related enhancement in MMNm response was obtained for rising but not falling frequency sweep contours. A hemispheric asymmetry in the MMNm response pattern was observed corresponding to the directionality of frequency sweeps. Contrary to psychophysical findings, we report a temporal window as short as 10 ms sufficient to elicit a robust MMNm response to a directional change in speech-relevant frequency contours. The results suggest that auditory cortex requires extremely brief temporal window to implicitly differentiate a dynamic change in frequency of linguistically relevant pitch contours. That the brain is extremely sensitive to fine spectral changes contained in speech-relevant glides provides cortical evidence for the ecological importance of FM sweeps in speech processing. [ABSTRACT FROM AUTHOR]

Objective: The main objective of this work was to evaluate the performance of recently developed dynamic-mechanical thermoanalysis (DMTA) test as a rapid rheological alternative to conventional freeze-thaw cycling for accelerated stability testing of oil-in-water (O/W) emulsions. Significance: The rational for this approach was reducing the time needed for product and process development and optimization, potentially through shortening the time needed for stability evaluation, in order to keep the pace with high formulating turnover imposed by increasing demands for placing products on the market, that is, to facilitate decision making in R&D and QC settings. Methods: Six model O/W emulsions were designed, rheologically characterized (continuous rotational and oscillatory tests), and subjected to stability evaluation through freeze-thaw test in stability chamber and DMTA tests using an air-bearing rheometer. Results: Investigated samples were characterized by favorized shear-thinning flow behavior with yield point. The elastic behavior dominated the viscous one in the LVE region of amplitude sweeps, as well as in the frequency sweeps of used frequency range. Statistical method comparison studies demonstrated that the results obtained by freeze-thaw test, routinely used for accelerated stability testing of emulsions, were in good accordance with those obtained with DMTA tests, whereas the time needed for stability assessment was significantly reduced (2–6 h versus 12 days). Conclusions: In summary, DMTA test proved to be an expeditious alternative for accelerated freeze-thaw stability testing of O/W emulsions, with great promise in new product development and optimization (R&D), as well as in determination of borderline product batches status (QC). [ABSTRACT FROM AUTHOR]

[Display omitted] High-field electron paramagnetic resonance (EPR) measurements are indispensable for a better understanding of dynamic nuclear polarization (DNP), which relies on polarization transfer between electron and nuclear spins. DNP experiments are typically performed at high > 7 T magnetic fields and low ≤ 100 K temperatures, while EPR instrumentation capable of EPR measurements under these conditions is scarce. In this paper, we describe the CW EPR capabilities of a dual DNP/EPR spectrometer that is designed to carry out EPR experiments under "DNP conditions" at 14 and 7 T. In the first part, we present the design of this instrument, highlighting the choices made to allow for both DNP and EPR operations. The spectrometer uses a sweepable cryogen-free magnet with NMR-grade homogeneity, a closed-cycle cooling system, a quasi-optical induction mode bridge, and a superheterodyne receiver system. The probe design is optimized for low heat load and fast sample exchange under cryogenic conditions. The spectrometer can operate in frequency and field sweep modes, including wide field sweeps using the main coil of the magnet. In the second part, we present EPR spectra acquired over a wide range of samples and operating conditions, illustrating the CW EPR capabilities of the instrument. [ABSTRACT FROM AUTHOR]

In computational electromagnetism, the radar signature of a target usually requires solving repeated electromagnetic scattering problems associated to plane waves illuminating the target with varying frequency and incident angle. When the problem is large scale, strategies based on repeated solver calls usually lead to prohibitive computational costs. This is especially the case when the solver relies on an integral equation discretized using the boundary element method (BEM), as this amounts to solving numerous complex, unsymmetrical and fully populated linear systems. In this work, reduced order models (ROMs) are built in order to rapidly and accurately approximate the solutions for illuminating waves with frequencies and incident angles within bands of interest. In the context of the BEM, the success of a ROM essentially depends on the ability to decouple the frequency from the Green kernels of the underlying integral equation. In this work, we present a methodology for achieving such decoupling that combines the Empirical Interpolation Method (EIM) with the notion of local adaptivity. We use our approximation of the frequency-dependent BEM operator in a locally adaptive non-intrusive reduced basis method. The proposed strategy is fully non-intrusive, in the sense that it only requires the ability to perform matrix–vector products with standard BEM operators. We illustrate our methodology on real-life electromagnetic scattering problems solved by the Combined Field Integral Equation (CFIE) and with matrix–vector products accelerated with the fast-multipole method (FMM). [ABSTRACT FROM AUTHOR]

Salt erosion can exert significant influence on the deformation resistance performance of bitumen. Zero shear viscosity (ZSV) is presently considered as a powerful indicator to evaluate the permanent deformation resistance of bitumen. In this study, the ZSV evolution of bitumen under different salt erosion conditions was investigated, and the applicability of different calculation methods in characterizing the ZSV of salt-eroded bitumen was evaluated. The Dynamic Shear Rheometer (DSR) was employed to conduct the frequency sweep test and shear rate sweep test. The complex viscosity (η *) master curve was extended to improve the ZSV fitting accuracy. Fourier Transform Infrared Spectroscopy (FTIR) test was performed to investigate the ZSV evolution mechanism of salt-eroded bitumen. It can be obtained from the results that after eliminating the non-Newtonian plateau region, the target error (TE) values reduced by over 95 %, compared with original shear rate sweep test. The TE values calculated by extended master curve were far less than conventional frequency sweep test, and were all close to 0. In addition, the ZSV calculated by extended mater curve of bitumen treated with water freeze-thaw, water immersion, salt freeze-thaw, and saline immersion increased by 53.9 %, 46.0 %, 51.8 %, and 82.82 %, respectively, compared with untreated bitumen. Meanwhile, there existed a favorable linear correlation between the ZSV and sulfoxide index, whose coefficient of determination values were all greater than 0.99. The results can provide some theoretical basis for the damage mechanism investigation of salt-eroded bitumen, and provide some novel ideas for the ZSV calculation of bitumen. • Evaluate the ZSV and its reliability for application on salt-eroded bitumen. • Improve the ZSV calculation accuracy based on rheological models. • Explore the ZSV evolution mechanism of salt-eroded bitumen. [ABSTRACT FROM AUTHOR]

This paper presents the characterization of the modal frequencies and the modal orientation of the axisymmetric resonators in Coriolis vibratory gyroscopes based on the approaches of the frequency sweep and the ring down. The modal frequencies and the orientation of the stiffness axis are the key parameters for the mechanical correction of the stiffness imperfections. The frequency sweep method utilizes the zero and the poles in the magnitude-frequency responses of the two-dimensional transfer function to extract the modal orientation information within the frequency domain. The ring down method makes use of the peak and the valley values of the beat signals at the readout electrodes to obtain the modal orientation and the coefficient of the nonlinear stiffness directly within the time domain. The proposed approaches were verified via a silicon ring resonator designed for gyroscopic sensing and the modal information from the experiments exhibited a good agreement between the methods of the frequency sweep and the ring down.

In this paper, we realize a series of 2-GHz wide rectangular optical filters based on the stimulated Brillouin scattering (SBS) effect in optical fiber with a frequency-swept pump and gain feedback compensation scheme. The frequency sweep pump period is a key parameter to achieve acceptable signal performance in the frequency-swept pump based SBS gain filter. We evaluate the system performance of the signal, which is fed into the SBS filter based on frequency-swept pump with different sweep periods ranging from 0.1 to 100 μs, in terms of eye diagrams and bit-error rate (BER) after 12.5 and 25 km of fiber transmission, respectively. Both 500-Mb/s and 1-Gb/s on-off-keying (OOK) signals are used for real-time signal quality evaluation. The optimum eye diagram and BER performance are achieved after 25 km transmission under a 1 μs frequency sweep pump period, as well as after 12.5-km transmission under a 0.5 μs sweep period. The experimental results show that the optimal frequency sweep pump period is always around 1/120 of the signal propagation time in the fiber for different transmission length, providing a guideline on the design of the frequency-swept pump based SBS gain filter and its applications.

Optoelectronic devices which play important roles in high-speed optical fiber networks can offer effective measurement methods for optoelectronic devices including optical modulators and photodetectors. Precise optical signal modulation is required for measurement applications. This paper focuses on high-speed and precise optical modulation devices and their application to device measurement. Optical modulators using electro-optic effect offers precise control of lightwaves for wideband signals. As examples, this paper describes frequency response measurement of photodetectors using high-precision amplitude modulation and wavelength domain measurement of optical filters using fast optical frequency sweep. Precise and high-speed modulation can be achieved by active trimming which compensates device structure imbalance due to fabrication error, where preciseness can be described by on-off extinction ratio. A Mach-Zehnder modulator with sub Mach-Zehnder interferometors can offer high extinction-ratio optical intensity modulation, which can be used for precise optoelectronic frequency response measurement. Precise modulation would be also useful for multi-level modulation schemes. To investigate impact of finite extinction ratio on optical modulation, duobinary modulation with small signal operation was demonstrated. For optical frequency domain analysis, single sideband modulation, which shifts optical frequency, can be used for generation of stimulus signals. Rapid measurement of optical filters was performed by using an optical sweeper consisting of an integrated Mach-Zehnder modulator for optical frequency control and an arbitrary waveform generator for generation of a source frequency chirp signal.

The Warm mix asphalt (WMA) industry has attracted considerable attention due to the additives'ability to reduce the mixing and compaction temperatures of the asphalt mixture. Deurex has showed its potential of being a new additive in this industry. However, properties of Deurex-modified binders have not been studied in details. The objective of this study was to investigate the rheological properties of binders containing various types of WMA additives through conventional test, viscosity, failure temperature, frequency and amplitude sweep. The study included three binder sources (two 60/80 pen asphalt, and styrene–butadiene–styrene (SBS)-modified asphalt), two types of WMA additives (Deurex and Sasobit) and control binders. The results indicated that both Sasobit and Deurex had similar effect on viscosity reduction regardless of asphalt types. The results also indicates that binders containing Deurex had better high-temperature rutting resistance, concerning increased softening point, fail temperature, stiffness and storage modulus. In addition, temperature sweep, frequency sweep and amplitude test show that the Sasobit-modified asphalt binders exhibit a slightly higher storage modulus and complex modulus but a lower phase angle than the Deurex-modified asphalt. [ABSTRACT FROM AUTHOR]