Mechanical Fourier Series Generator: Theory and Practice

2007 ◽  
Author(s):  
Izhak Bucher ◽  
Gal Avivi
Keyword(s):  
Fourier Series ◽  
Theory And Practice ◽  
Response Patterns ◽  
Mechanical Device ◽  
Periodic Response ◽  
Basic Frequency

In this paper the theory behind a Mechanical device that lends itself to producing periodic response patterns under small excitation levels is described. It turns out that certain symmetry features that are presented here are useful in the design of the desired Mechanical device. It will be shown mathematically that the compliance of the structure can be made high at frequencies that are integer multiples of a basic frequency while the compliance is zero at other frequencies where no energy is to be conveyed the oscillating element. As a result, this structure lends itself to producing periodic oscilations under small excitation levels.

On-line frequency adaptation and movement imitation for rhythmic robotic tasks

2011 ◽  
Vol 30 (14) ◽  
pp. 1775-1788 ◽  
Author(s):  
Tadej Petrič ◽  
Andrej Gams ◽  
Auke Jan Ijspeert ◽  
Leon Žlajpah
Keyword(s):  
Signal Processing ◽  
Fourier Series ◽  
Feedback Loop ◽  
Periodic Signal ◽  
Basic Frequency ◽  
Additional Signal ◽  
Emg Signal ◽  
Non Linear ◽  
Novel Method ◽  
Robotic Tasks

In this paper we present a novel method to obtain the basic frequency of an unknown periodic signal with an arbitrary waveform, which can work online with no additional signal processing or logical operations. The method originates from non-linear dynamical systems for frequency extraction, which are based on adaptive frequency oscillators in a feedback loop. In previous work, we had developed a method that could extract separate frequency components by using several adaptive frequency oscillators in a loop, but that method required a logical algorithm to identify the basic frequency. The novel method presented here uses a Fourier series representation in the feedback loop combined with a single oscillator. In this way it can extract the frequency and the phase of an unknown periodic signal in real time and without any additional signal processing or preprocessing. The method determines the Fourier series coefficients and can be used for dynamic Fourier series implementation. The proposed method can be used for the control of rhythmic robotic tasks, where only the extraction of the basic frequency is crucial. For demonstration several highly non-linear and dynamic periodic robotic tasks are shown, including also a task where an electromyography (EMG) signal is used in a feedback loop.

Addressing the Content Vocabulary With Core: Theory and Practice for Nonliterate or Emerging Literate Students

2012 ◽  
Vol 21 (3) ◽  
pp. 74-81 ◽  
Author(s):  
Debbie Witkowski ◽  
Bruce Baker
Keyword(s):  
Communication Skills ◽  
High Performance ◽  
Theory And Practice ◽  
Written Communication ◽  
Academic Tasks ◽  
Meaningful Participation ◽  
Core Theory ◽  
Communication Needs ◽  
Core Vocabulary ◽  
Personal Success

Abstract In the early elementary grades, the primary emphasis is on developing skills crucial to future academic and personal success—specifically oral and written communication skills. These skills are vital to student success as well as to meaningful participation in the classroom and interaction with peers. Children with complex communication needs (CCN) may require the use of high-performance speech generating devices (SGDs). The challenges for these students are further complicated by the task of learning language at a time when they are expected to apply their linguistic skills to academic tasks. However, by focusing on core vocabulary as a primary vehicle for instruction, educators can equip students who use SGDs to develop language skills and be competitive in the classroom. In this article, we will define core vocabulary and provide theoretical and practical insights into integrating it into the classroom routine for developing oral and written communication skills.

Stimulus Ratio Effects on Speech Discrimination by Children and Adults

1991 ◽  
Vol 34 (3) ◽  
pp. 671-678 ◽  
Author(s):  
Joan E. Sussman
Keyword(s):  
Discrimination Task ◽  
Response Pattern ◽  
Response Patterns ◽  
Speech Discrimination ◽  
Adult Group ◽  
Discrimination Accuracy ◽  
Formant Frequency ◽  
Response Strategies ◽  
Place Of Articulation ◽  
Adults And Children

This investigation examined the response strategies and discrimination accuracy of adults and children aged 5–10 as the ratio of same to different trials was varied across three conditions of a “change/no-change” discrimination task. The conditions varied as follows: (a) a ratio of one-third same to two-thirds different trials (33% same), (b) an equal ratio of same to different trials (50% same), and (c) a ratio of two-thirds same to one-third different trials (67% same). Stimuli were synthetic consonant-vowel syllables that changed along a place of articulation dimension by formant frequency transition. Results showed that all subjects changed their response strategies depending on the ratio of same-to-different trials. The most lax response pattern was observed for the 50% same condition, and the most conservative pattern was observed for the 67% same condition. Adult response patterns were most conservative across condition. Differences in discrimination accuracy as measured by P(C) were found, with the largest difference in the 5- to 6-year-old group and the smallest change in the adult group. These findings suggest that children’s response strategies, like those of adults, can be manipulated by changing the ratio of same-to-different trials. Furthermore, interpretation of sensitivity measures must be referenced to task variables such as the ratio of same-to-different trials.

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