12-PULSE RECTIFIER WITH TWO DCM BOOST-TYPE HALF-CONTROLLED BRIDGES FOR VARIABLE-INPUT-FREQUENCY APPLICATIONS

ABSTRACTAlthough it has been often hypothesized that children learn to produce new sound patterns first in frequently heard words, the available evidence in support of this claim is inconclusive. To re-examine this question, we conducted a survival analysis of word-initial consonant clusters produced by three children in the Providence Corpus (0 ; 11–4 ; 0). The analysis took account of several lexical factors in addition to lexical input frequency, including the age of first production, production frequency, neighborhood density and number of phonemes. The results showed that lexical input frequency was a significant predictor of the age at which the accuracy level of cluster production in each word first reached 80%. The magnitude of the frequency effect differed across cluster types. Our findings indicate that some of the between-word variance found in the development of sound production can indeed be attributed to the frequency of words in the child's ambient language.

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Direct Fourier migration for vertical velocity variations

Geophysics ◽

10.1190/1.1487096 ◽

2001 ◽

Vol 66 (5) ◽

pp. 1504-1514 ◽

Cited By ~ 9

Author(s):

Gary F. Margrave

Keyword(s):

Phase Shift ◽

Vertical Velocity ◽

Constant Velocity ◽

Delta Function ◽

Fourier Domain ◽

Input Frequency ◽

Output Frequency ◽

Dirac Delta ◽

Change Of Variables ◽

Velocity Variations

The Stolt f‐x migration algorithm is a direct (i.e. nonrecursive) Fourier‐domain technique based on a change of variables, or equivalently a mapping, that converts the unmigrated spectrum to the migrated spectrum. The algorithm is simple and efficient but limited to constant velocity. A v(z) f‐k migration method, capable of very high accuracy for vertical velocity variations, can be formulated as a nonstationary filter that avoids the change of variables. The result is a direct Fourier‐domain process that, for each wavenumber, applies a nonstationary migration filter to a vector of input frequency samples to create a vector of output frequency samples. The filter matrix is analytically specified in the mixed domain of input frequency and migrated time. It can be moved to the full‐Fourier domain of input frequency and output frequency by a fast Fourier transform. When applied for constant velocity, the v(z) f‐k algorithm is slower than the Stolt method but without the usual artifacts related to complex‐valued frequency‐domain interpolation. Vertical velocity variations, through an rms‐velocity (straight‐ray) assumption, are handled by the v(z) f‐k method with no additional cost. Greater accuracy at slight additional expense is obtained by extending the method to a WKBJ phase‐shift integral. This has the same accuracy as recursive phase shift and is similar in cost. For constant velocity, the full‐Fourier domain migration filter is a discrete approximation to a Dirac delta function whose singularity tracks along a hyperbola determined by the migration velocity. For variable velocity, the migration filter has significant energy between hyperbolic trajectories determined by the minimum and maximum instantaneous velocities. The full‐Fourier domain offers interesting conceptual parallels to Stolt’s algorithm. However, unless a more efficient method of calculating the Fourier filter matrix can be found, the mixed‐domain method will be faster. The mixed‐domain nonstationary filter moves the input data from the Fourier domain to the migrated time domain as it migrates. It is faster because the migration filter is known analytically in the mixed domain.

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A Compliant Transmission Mechanism With Intermittent Contacts for Cycle-Doubling

Journal of Mechanical Design ◽

10.1115/1.2403774 ◽

2006 ◽

Vol 129 (1) ◽

pp. 114-121 ◽

Cited By ~ 3

Author(s):

Nilesh D. Mankame ◽

G. K. Ananthasuresh

Keyword(s):

Finite Element ◽

Conceptual Design ◽

Finite Element Simulations ◽

Nonlinear Finite Element ◽

Transmission Mechanism ◽

Input Frequency ◽

Length Scales ◽

Wide Range ◽

Macro Scale ◽

Functional Prototype

A novel compliant transmission mechanism that doubles the frequency of a cyclic input is presented in this paper. The compliant cycle-doubler is a contact-aided compliant mechanism that uses intermittent contact between itself and a rigid surface. The conceptual design for the cycle-doubler was obtained using topology optimization in our earlier work. In this paper, a detailed design procedure is presented for developing the topology solution into a functional prototype. The conceptual design obtained from the topology solution did not account for the effects of large displacements, friction, and manufacturing-induced features such as fillet radii. Detailed nonlinear finite element analyses and experimental results from quasi-static tests on a macro-scale prototype are used in this paper to understand the influence of the above factors and to guide the design of the functional prototype. Although the conceptual design is based on the assumption of quasi-static operation, the modified design is shown to work well in a dynamic setting for low operating frequencies via finite element simulations. The cycle-doubler design is a monolithic elastic body that can be manufactured from a variety of materials and over a range of length scales. This makes the design scalable and thus adaptable to a wide range of operating frequencies. Explicit dynamic nonlinear finite element simulations are used to verify the functionality of the design at two different length scales: macro (device footprint of a square of 170mm side) at an input frequency of 7.8Hz; and meso (device footprint of a square of 3.78mm side) at an input frequency of 1kHz.

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Insights into associative long-term potentiation from computational models of NMDA receptor-mediated calcium influx and intracellular calcium concentration changes

Journal of Neurophysiology ◽

10.1152/jn.1990.63.5.1148 ◽

1990 ◽

Vol 63 (5) ◽

pp. 1148-1168 ◽

Cited By ~ 104

Author(s):

W. R. Holmes ◽

W. B. Levy

Keyword(s):

Experimental Data ◽

Nmda Receptor ◽

Nmda Receptors ◽

Dendritic Spine ◽

Long Term Potentiation ◽

Input Frequency ◽

Spine Head ◽

Term Potentiation ◽

Concentration Changes

1. Because induction of associative long-term potentiation (LTP) in the dentate gyrus is thought to depend on Ca2+ influx through channels controlled by N-methyl-D-aspartate (NMDA) receptors, quantitative modeling was performed of synaptically mediated Ca2+ influx as a function of synaptic coactivation. The goal was to determine whether Ca2+ influx through NMDA-receptor channels was, by itself, sufficient to explain associative LTP, including control experiments and the temporal requirements of LTP. 2. Ca2+ influx through NMDA-receptor channels was modeled at a synapse on a dendritic spine of a reconstructed hippocampal dentate granule cell when 1-115 synapses on spines at different dendritic locations were activated eight times at frequencies of 10-800 Hz. The resulting change in [Ca2+] in the spine head was estimated from the Ca2+ influx with the use of a model of a dendritic spine that included Ca2+ buffers, pumps, and diffusion. 3. To use a compelling model of synaptic activation, we developed quantitative descriptions of the NMDA and non-NMDA receptor-mediated conductances consistent with available experimental data. The experimental data reported for NMDA and non-NMDA receptor-channel properties and data from other non-LTP experiments that separated the NMDA and non-NMDA receptor-mediated components of synaptic events proved to be limiting for particular synaptic variables. Relative to the non-NMDA glutamate-type receptors, 1) the unbinding of transmitter from NMDA receptors had to be slow, 2) the transition from the bound NMDA receptor-transmitter complex to the open channel state had to be even slower, and 3) the average number of NMDA-receptor channels at a single activated synapse on a single spine head that were open and conducting at a given moment in time had to be very small (usually less than 1). 4. With the use of these quantitative synaptic conductance descriptions. Ca2+ influx through NMDA-receptor channels at a synapse was computed for a variety of conditions. For a constant number of pulses, Ca2+ influx was calculated as a function of input frequency and the number of coactivated synapses. When few synapses were coactivated, Ca2+ influx was small, even for high-frequency activation. However, with larger numbers of coactivated synapses, there was a steep increase in Ca2+ influx with increasing input frequency because of the voltage-dependent nature of the NMDA receptor-mediated conductance. Nevertheless, total Ca2+ influx was never increased more than fourfold by increasing input frequency or the number of coactivated synapses.(ABSTRACT TRUNCATED AT 400 WORDS)

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Changes of synaptic input frequency in the dentate gyrus induce feedback regulation of synaptic strength in vivo

Neuroscience Research ◽

10.1016/j.neures.2010.07.1505 ◽

2010 ◽

Vol 68 ◽

pp. e340

Author(s):

Daisuke Miyamoto ◽

Hiroshi Nomura ◽

Norio Matsuki

Keyword(s):

Dentate Gyrus ◽

Synaptic Input ◽

Feedback Regulation ◽

Synaptic Strength ◽

Input Frequency

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Harmonic-suppressed quadrature-input frequency divider for OFDM systems

Journal of Semiconductors ◽

10.1088/1674-4926/32/12/125005 ◽

2011 ◽

Vol 32 (12) ◽

pp. 125005

Author(s):

Haipeng Fu ◽

Junyan Ren ◽

Wei Li ◽

Ning Li

Keyword(s):

Frequency Divider ◽

Input Frequency ◽

Ofdm Systems

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Process Optimization of Ultrasonic Shot Peening by Realistic Modeling of Beads Motion

Volume 6B: Materials and Fabrication ◽

10.1115/pvp2014-28424 ◽

2014 ◽

Author(s):

Alexandre Brosse ◽

Simon Le Moal ◽

Rémi Lacroix ◽

Philippe Mourgue ◽

Vincent Robin ◽

...

Keyword(s):

Numerical Model ◽

Shot Peening ◽

High Frequency ◽

High Speed ◽

Nuclear Industry ◽

Input Frequency ◽

Realistic Modeling ◽

Ultrasonic Shot Peening ◽

Small Steel

In the nuclear industry surface mechanical treatments are used in order to improve the surface integrity of the component, which increases their lifetime regarding corrosion and fatigue damages. A good understanding of these processes and their consequences is required to ensure the efficiency and perpetuity of such mitigation treatment. This study focuses on the ultrasonic shot peening process. It consists in shooting at high speed small steel beads on the part to be treated by using a high frequency vibration device. Parameters such as the number and the size of beads, the input frequency and the dimensions of the chamber can induce large ranges of impact velocity and coverage. In order to help manufacturers to control the treatment applied on their components, a numerical model has been developed. It accounts for the shocks of the beads against the walls of the chamber, the peening head and between beads, describing their motions accurately. In this paper, we will introduce the numerical model developed to simulate the motions of beads in the peening chamber. Special attention will be taken to the determination of the restitution rates related to the different materials. Results of the model will be shown for different process parameter (e.g. the number of beads), and a thorough analysis of their effects on the workpiece will be presented, including a comparison with some experimental results.

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Genetic and environmental effects in L1 phonological acquisitionThe case of consonant harmony in Greek child speech

Journal of Greek Linguistics ◽

10.1075/jgl.8.04tza ◽

2007 ◽

Vol 8 (1) ◽

pp. 5-30 ◽

Cited By ~ 2

Author(s):

Marina Tzakosta

Keyword(s):

Environmental Effects ◽

Input Frequency ◽

Stressed Syllable ◽

Place Of Articulation ◽

Consonant Harmony ◽

Multiple Factors ◽

Greek Child ◽

Ambient Language ◽

Child Speech ◽

Manner Of Articulation

AbstractConsonant harmony (CH) is a phenomenon commonly found in child language. Cross-linguistically, Place of Articulation (PoA), specifically the Coronal Node, undergoes CH, while regressive harmony seems to be the preferred directionality that CH takes (cf. Goad 2001a, b; Levelt 1994; Rose 2000, 2001). In the present study, drawing on naturalistic data from nine children acquiring Greek L1, we place emphasis on the fact that multiple factors need to be considered in parallel, in order to account for CH patterns: Not only PoA, but also Manner of Articulation (MoA) contributes to CH; consequently, (de)voicing or continuity harmony emerges. Although regressive harmony is generally favoured, markedness scales and word stress highly affect directionality. Coronal, stop and voiceless segments trigger and undergo CH depending on their degree of prominence and their position in the word. Harmony can be partial or full, i.e. either place or manner or both place and manner of articulation are targeted. Progressive harmony emerges when the triggers belong to the stressed syllable or when they are stops. Cases of double, bidirectional and recursive harmony are also reported. In general, Greek CH patterns are the product of combined factors determined by phonological principles and input frequency in the ambient language. In other words, the degree to which Greek CH patterns are different from cross-linguistic findings depends on the combination of UG principles and language specific/environmental effects, as well as the prominence of certain of these factors over others.

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