Improved DC/AC interface inverter for high-frequency space applications

1993 ◽  
Vol 29 (4) ◽  
pp. 1150-1163 ◽  
Author(s):  
P. Jain ◽  
M. Tanju
Keyword(s):  
High Frequency ◽  
Space Applications ◽  
Frequency Space

scholarly journals On the Effectiveness of Low Frequency Perturbations

2019 ◽  
Author(s):  
Yash Sharma ◽  
Gavin Weiguang Ding ◽  
Marcus A. Brubaker
Keyword(s):  
High Frequency ◽  
State Of The Art ◽  
Low Frequency ◽  
Human Perception ◽  
Search Space ◽  
Frequency Space ◽  
Performance Improvements ◽  
Frequency Regime ◽  
Frequency Components ◽  
Norm Constraint

Carefully crafted, often imperceptible, adversarial perturbations have been shown to cause state-of-the-art models to yield extremely inaccurate outputs, rendering them unsuitable for safety-critical application domains. In addition, recent work has shown that constraining the attack space to a low frequency regime is particularly effective. Yet, it remains unclear whether this is due to generally constraining the attack search space or specifically removing high frequency components from consideration. By systematically controlling the frequency components of the perturbation, evaluating against the top-placing defense submissions in the NeurIPS 2017 competition, we empirically show that performance improvements in both the white-box and black-box transfer settings are yielded only when low frequency components are preserved. In fact, the defended models based on adversarial training are roughly as vulnerable to low frequency perturbations as undefended models, suggesting that the purported robustness of state-of-the-art ImageNet defenses is reliant upon adversarial perturbations being high frequency in nature. We do find that under L-inf-norm constraint 16/255, the competition distortion bound, low frequency perturbations are indeed perceptible. This questions the use of the L-inf-norm, in particular, as a distortion metric, and, in turn, suggests that explicitly considering the frequency space is promising for learning robust models which better align with human perception.

On the Fatigue at Very High Frequency — Part I: Theoretical and Variational Formulation

1991 ◽  
Vol 113 (2) ◽  
pp. 205-209 ◽  
Author(s):  
Kong Xiangan ◽  
K. Saanouni ◽  
C. Bathias
Keyword(s):  
High Frequency ◽  
Time Integration ◽  
Classical Problem ◽  
Fatigue Tests ◽  
Evolution Problem ◽  
Very High Frequency ◽  
Thermoelastic Wave ◽  
Frequency Space ◽  
Endurance Tests ◽  
Very High

This first part of our study is concerned with the theoretical and variational formulations of the problem of elastic cyclic loading at very high frequency (or acoustic fatigue). The problem is treated by using the theory of longitudinal thermoelastic wave motion in a finite medium with and without running crack. Two methods are used to formulate the evolution problem: the first one deals with the use of classical time integration schema, and the second uses the Fourier transformation to solve the evolution problem in the frequency space. Comparison of our results with some closed form solutions of some classical problem is presented. In a second paper this method is used to calculate thermo-mechanical fields in specimens used in ultrasonic fatigue tests (endurance tests and crack growth tests).

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