Combined Effects Of Frequency Research Articles

Characterization of heat transfer enhancement for an oscillating flat plate-fin

Heat transfer augmentation is of paramount importance in energy transfer and storage systems and the idea of using the inherent vibrations in a system to enhance heat transfer needs to be thoroughly researched upon. The current study numerically investigates an infinitesimally thin plate-fin undergoing forced oscillations over a range of amplitudes and frequencies in the presence of an approach flow. Reduced frequencies of 0.25 ≤ k ≤ 16 and plunge amplitudes of 0.03125 ≤ h ≤ 8 are investigated at Re = 100 and Pr = 0.71. It is shown that the combined effect of frequency and amplitude on heat transfer enhancement can be accounted for as a single parameter “plunge velocity” (0.25 ≤ kh ≤ 4) instead of the individual frequency and amplitude values. For kh > 0.5 a significant increase in Nusselt number (Nu) is observed compared to a stationary plate. With increasing kh or more vigorous oscillations, the increase in Nu becomes more prominent and similar trends and comparable magnitudes were observed for a constant kh value. Unlike the hydrodynamic counterpart of the study, both Leading Edge Vortices (LEVs) and Trailing Edge Vortices (TEVs) are found to act positively to induce enhanced heat transfer on the plate. Finally, the dependence of heat transfer augmentation on the frequency and amplitude of vibration is quantified with a simple parameterization for a plate-fin in a fluid medium.

Combined effects of frequency and higher-order effects on soliton conversion in an erbium fiber with inhomogeneous broadening

In this paper, soliton propagation in an erbium-doped fiber with inhomogeneous broadening is considered which can be described by the inhomogeneous Hirota– Maxwell–Bloch equations. The Darboux transformation method is employed to generate the soliton solution through a linear eigenvalue problem. In particular, our results demonstrate explicitly that a soliton can be converted into various nonlinear waves such as periodic wave, anti-kink soliton and flat-top soliton in the presence of higher-order effects with inhomogeneous broadening. Additionally, we found that higher-order coefficients have strong influence on the soliton transition while frequency is only responsible for phase shift. The results might be of certain value for the study of the soliton management and soliton conversion.

A Bootstrapping Model of Frequency and Context Effects in Word Learning.

Prior research has shown that people can learn many nouns (i.e., word-object mappings) from a short series of ambiguous situations containing multiple words and objects. For successful cross-situational learning, people must approximately track which words and referents co-occur most frequently. This study investigates the effects of allowing some word-referent pairs to appear more frequently than others, as is true in real-world learning environments. Surprisingly, high-frequency pairs are not always learned better, but can also boost learning of other pairs. Using a recent associative model (Kachergis, Yu, & Shiffrin, 2012), we explain how mixing pairs of different frequencies can bootstrap late learning of the low-frequency pairs based on early learning of higher frequency pairs. We also manipulate contextual diversity, the number of pairs a given pair appears with across training, since it is naturalistically confounded with frequency. The associative model has competing familiarity and uncertainty biases, and their interaction is able to capture the individual and combined effects of frequency and contextual diversity on human learning. Two other recent word-learning models do not account for the behavioral findings.

Cumulative Response to Sequences of Terror Attacks Varying in Frequency and Trajectory.

There is a paucity of research examining public response to the cumulative effects of multiple related extreme events over time. We investigated the separate and combined effects of frequency and trajectory of terrorist attacks. A scenario simulation of a series of gas station bombings in Southern California was developed to evaluate respondents' affect, risk perception, and intended avoidance behavior using a 3 (frequency; low vs. medium vs. high) by 3 (trajectory; increasing vs. constant vs. decreasing) factorial design. For each of the nine conditions, three videos were created to simulate news broadcasts documenting the attacks over a three-week period. A total of 275 respondents were included in the analysis. Results from analysis of covariances (ANCOVAs) indicate that trajectory of the sequential attacks (increasing or decreasing in frequency) predicts negative affect, risk perception, and avoidance behavior. In contrast, frequency predicts neither negative affect, positive affect, risk perception, nor intended avoidance behavior. Results from structural equation modeling (SEM) further indicate that the effect of negative affect on behavioral intention is mediated by risk perception and the effect of trajectory on risk perception is partially mediated by negative affect. In addition, both ANCOVAs and SEM model results suggest that (1) females experience less positive affect and perceive more risk than males, (2) respondents with higher income perceive more risk, and (3) younger respondents are more likely to modify their behavior to avoid the risk of future attacks.

The combined effect of feed frequency and ration size of diets with and without microbial biomass on the growth and feed conversion of juvenilePenaeus monodon

Feed management strategies that maximize shrimp growth and optimize feed utilization are critical to the cost-effectiveness of production. In this study, juvenile Penaeus monodon (~3 g) were cultured for 6 weeks in a laboratory-based clear-water tank system. The experiment design was a three-way factorial with two diets (Diet A – standard industry formulation or Diet B – the same diet with 10% microbial biomass), two feed frequencies (twice or six times daily) and three rations (60%, 80% and 100% of satiation). The results demonstrated clear growth benefits of feeding more than two times per day and feed efficiency benefits of a restricted ration. There was also a significant interaction between frequency and ration, which demonstrated that growth improved using six feeds compared with two feeds as ration amount decreased. The effects of frequency and ration were consistent for both diets; however, the addition of a microbial biomass provided significant growth improvements across all treatments. These outcomes define the gains produced by the combined effect of frequency and ration and suggest a compromise between feed utilization and feeding effort for adoption in feed management strategies.

Extraction of ursolic acid from Ocimum sanctum by ultrasound: Process intensification and kinetic studies

The present work describes the application of ultrasound for the intensification of ursolic acid (UA) extraction from Ocimum sanctum (OS). The different process parameters such as extraction time, solid to solvent ratio, extraction temperature, ultrasound power and frequency have been optimized based on the maximum extraction yield. The maximum yield 16.47mg UA/g of OS was obtained at optimum extraction conditions (extraction time 12min, solid to solvent ratio 1:30, temperature 45°C and frequency of 25kHz). Effect of 25kHz and 40kHz has been observed at different power dissipation. The combined effect of frequency and ultrasound power gives a better extraction yield while temperature has no significant effect on extraction. The yield obtained with ultrasound-assisted extraction (UAE) has been compared with batch and soxhlet extraction of UA. This research clearly shows that the UAE method is quite better than conventional extraction as it effectively reduces the extraction time of UA to just 12min without deterioration. Further, the kinetics of the extraction is investigated by the Peleg's model. The extraction rate constant, initial extraction rate and equilibrium concentration for all experimental conditions have been predicted. The mathematical model applied showed a good agreement with the experimental results.

Impact of high-intensity pulsed electric fields variables on vitamin C, anthocyanins and antioxidant capacity of strawberry juice

A response surface methodology was used to determine the combined effect of HIPEF critical processing conditions on vitamin C, anthocyanins and antioxidant capacity of strawberry juice. Keeping constant the electric field strength at 35 kV/cm and the treatment time at 1000 μs, the treatments were set at frequencies from 50 to 250 Hz, pulse width from 1 to 7 μs using monopolar or bipolar mode. A second order response function covering the whole range of experimental conditions was obtained for each health-related compound. Strawberry juice antioxidant potential was affected linearly by frequency, pulse width and pulse polarity. The quadratic term of frequency and the combined effect of frequency and pulse width were also significant. HIPEF treatments conducted at 232 Hz with bipolar pulses of 1 μs led to strawberry juices with the greatest presence of health-related compounds. The evaluation of the HIPEF critical parameters influence on health-related compounds can contribute to achieve optimal processing conditions to obtain strawberry juices with high antioxidant potential.

Basic auditory processes involved in the analysis of speech sounds.

This paper reviews the basic aspects of auditory processing that play a role in the perception of speech. The frequency selectivity of the auditory system, as measured using masking experiments, is described and used to derive the internal representation of the spectrum (the excitation pattern) of speech sounds. The perception of timbre and distinctions in quality between vowels are related to both static and dynamic aspects of the spectra of sounds. The perception of pitch and its role in speech perception are described. Measures of the temporal resolution of the auditory system are described and a model of temporal resolution based on a sliding temporal integrator is outlined. The combined effects of frequency and temporal resolution can be modelled by calculation of the spectro-temporal excitation pattern, which gives good insight into the internal representation of speech sounds. For speech presented in quiet, the resolution of the auditory system in frequency and time usually markedly exceeds the resolution necessary for the identification or discrimination of speech sounds, which partly accounts for the robust nature of speech perception. However, for people with impaired hearing, speech perception is often much less robust.

The combined effect of frequency and load level on fatigue crack growth in stainless steel 304

The crack growth behavior in stainless steel 304 was investigated at 538°C. Compact tension specimens, 50 mm wide and 12.5 mm thick, were subjected to fatigue loading under R=0.05 load control. The combined effect of frequency (0.05 Hz≤ f≤10 Hz) and load level (6 kN≤ P max≤16 kN) on the crack growth rate was examined. Parameters Δ K and Δ J were shown to correlate crack growth rates reasonably well. Two ( f− P max) domains were suggested, in each of which crack growth can be characterized by a single d a/d N–Δ K equation. For Δ K<25 MPa m , crack growth rates appear to be independent of f× P max values, except at the lowest where faster crack growth occurred because of environmental effects. For Δ K>25 MPa m , crack growth rates were found higher for larger values of f× P max. The mode of crack growth was transgranular for all test conditions.

Electrochemical etching of CR39: Optimization of parameters for the processing of neutron-irradiated samples

ABSTRACT A study of the effects of frequency and electric field strength on the production of electrochemical etch spots in CR39 is described, with the intention of providing a sensitive neutron recorder with a consistent response. Experiments have been conducted with neutron energies from 0.57 to 6.0 MeV, frequencies from 2 kHz to 100 kHz, and electric field strengths from 8 kV cm−1 to 45 kV cm−1. The results indicate that the sensitivity and consistency require the optimization of the electric field strength, while the combined effects of frequency and electric field strength will determine the average size of the etch spots.

Non-isotropic redistribution effects on spectral line formation

The combined effects of frequency and angular redistribution are examined in slab and semi-infinite static isothermal atmospheres for the cases of pure Doppler damping and Doppler with natural damping using both the dipole and isotropic phase function. The main effect of angle-dependent redistribution is that photons which scatter more coherently in direction are re-emitted more coherently in frequency and this effect is enhanced by the dipole phase function. For the slab atmosphere it was generally found that the source functions, and hence the emergent intensities, for the angle-dependent redistribution were greater in the line core and smaller in the line wings than those obtained for angle-averaged or complete redistribution. For the semi-infinite atmosphere the behaviour of the results was the same as in the slab atmosphere except that in the line core the reverse was true for the emergent intensities and for the source functions at small optical depths.