Controlling Chaos by Bounded Self-Controlling Function Using Butterworth Filter Feedback

Data on climatic changes over thousands of years is needed for a better understanding of the shorter term variations which are of interest to man. For this purpose we measured the isotope composition (δD‰) of two adjacent ice cores drilled in the Dome C area. The time scale was established using the remarkably constant mean annual accumulation rate (37 kg m−2) determined by various techniques. The detailed isotope records were smoothed to filter out the δ value fluctuations not directly related to local temperature changes. With respect to conditions over the last 2.5 ka, the combined smoothed δ curve indicates a cooler climate from about 1800 to 1200 AD and a slightly warmer period from about 1200 to 700 AD. These periods may well correspond to the suggested world-wide Little Ice Age and medieval warm phase. Using the present δD‰/T°C measured at the surface, the maximum amplitude for these two periods, after smoothing with a low pass filter of 512 a, is approximately -0.35 and +0.3°C, respectively.

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An Efficient and Self-Adapted Approach to the Sharpening of Color Images

The Scientific World JOURNAL ◽

10.1155/2013/105945 ◽

2013 ◽

Vol 2013 ◽

pp. 1-18 ◽

Cited By ~ 1

Author(s):

Lih-Jen Kau ◽

Tien-Lin Lee

Keyword(s):

Color Image ◽

Color Images ◽

Natural Images ◽

Color Model ◽

Pass Filter ◽

Low Pass Filter ◽

Low Pass ◽

Effectiveness And Efficiency ◽

Global Statistics ◽

Original Information

An efficient approach to the sharpening of color images is proposed in this paper. For this, the image to be sharpened is first transformed to theHSVcolor model, and then only the channel ofValuewill be used for the process of sharpening while the other channels are left unchanged. We then apply a proposed edge detector and low-pass filter to the channel ofValueto pick out pixels around boundaries. After that, those pixels detected as around edges or boundaries are adjusted so that the boundary can be sharpened, and those nonedge pixels are kept unaltered. The increment or decrement magnitude that is to be added to those edge pixels is determined in an adaptive manner based on global statistics of the image and local statistics of the pixel to be sharpened. With the proposed approach, the discontinuities can be highlighted while most of the original information contained in the image can be retained. Finally, the adjusted channel ofValueand that ofHueandSaturationwill be integrated to get the sharpened color image. Extensive experiments on natural images will be given in this paper to highlight the effectiveness and efficiency of the proposed approach.

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Generalized Kalman-Yakubovich-Popov Lemma Based I-PD Controller Design for Ball and Plate System

Journal of Applied Mathematics ◽

10.1155/2013/854631 ◽

2013 ◽

Vol 2013 ◽

pp. 1-9 ◽

Cited By ~ 7

Author(s):

Shuichi Mochizuki ◽

Hiroyuki Ichihara

Keyword(s):

Controller Design ◽

Design Method ◽

Reference Signal ◽

Pass Filter ◽

Low Pass Filter ◽

Input Signals ◽

Low Pass ◽

Inclination Angles ◽

Pid Controller Design ◽

Plate System

The ball-on-plate balancing system has a camera that captures the ball position and a plate whose inclination angles are limited. This paper proposes a PID controller design method for the ball and plate system based on the generalized Kalman-Yakubovich-Popov lemma. The design method has two features: first, the structure of the controller called I-PD prevents large input signals against major changes in the reference signal; second, a low-pass filter is introduced into the feedback loop to reduce the influence of the measurement noise produced by the camera. Both simulations and experiments are used to evaluate the effectiveness of the design method.

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Isotope Climatic Record Over The Last 2.5 KA from Dome C, Antarctica, Ice cores

Annals of Glaciology ◽

10.3189/s0260305500002457 ◽

1982 ◽

Vol 3 ◽

pp. 17-22 ◽

Cited By ~ 3

Author(s):

J. P. Benoist ◽

J. Jouzel ◽

C. Lorius ◽

L. Merlivat ◽

M. Pourchet

Keyword(s):

Isotope Composition ◽

Accumulation Rate ◽

Maximum Amplitude ◽

Ice Cores ◽

Ice Age ◽

Pass Filter ◽

Low Pass Filter ◽

Temperature Changes ◽

Low Pass ◽

Climatic Record

Data on climatic changes over thousands of years is needed for a better understanding of the shorter term variations which are of interest to man. For this purpose we measured the isotope composition (δD‰) of two adjacent ice cores drilled in the Dome C area. The time scale was established using the remarkably constant mean annual accumulation rate (37 kg m−2) determined by various techniques. The detailed isotope records were smoothed to filter out the δ value fluctuations not directly related to local temperature changes. With respect to conditions over the last 2.5 ka, the combined smoothed δ curve indicates a cooler climate from about 1800 to 1200 AD and a slightly warmer period from about 1200 to 700 AD. These periods may well correspond to the suggested world-wide Little Ice Age and medieval warm phase. Using the present δD‰/T°C measured at the surface, the maximum amplitude for these two periods, after smoothing with a low pass filter of 512 a, is approximately -0.35 and +0.3°C, respectively.

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Robust Sliding Mode Control of a Unipolar Power Inverter

Energies ◽

10.3390/en14175405 ◽

2021 ◽

Vol 14 (17) ◽

pp. 5405

Author(s):

Muhammad Awais ◽

Abdul Rehman Yasin ◽

Mudassar Riaz ◽

Bilal Saqib ◽

Saba Zia ◽

...

Keyword(s):

Electromagnetic Interference ◽

Sliding Mode ◽

Practical Implementation ◽

Switching Frequency ◽

Sigmoid Function ◽

Pass Filter ◽

Low Pass Filter ◽

Pulse Width Modulated ◽

Simulation Based ◽

Low Pass

The key issue in the practical implementation of the sliding mode (SM) control–based power inverter is the variable switching frequency. This variable switching frequency not only induces electromagnetic interference (EMI) noise, but also reduces the efficiency of the inverter, as the size of the inductor and capacitor does not alter in tandem with this variable frequency. In this context, fixed switching frequency–based SM control techniques are proposed; however, some of them are too complex, while others compromise the inherent properties of SM control. In this research, a fixed frequency SM controller is proposed, which is based on the novel low-pass filter extraction of the discontinuous control signal. This allows the technique to be implemented with fewer hardware components, thus reducing the complications of implementation, while maintaining the robustness and parametric invariance of SM control. A simulation-based comparison with an existing pulse width modulated (PWM) SM controller is presented as the benchmark. In comparison with the sigmoid function SM controller, an improvement of 50% in the settling time along with zero steady-state errors and a further 37% and 42% improvement in the undershoot and overshoot, respectively, is reported in the simulation. A hardware setup is established to validate the proposed technique, which substantiates the simulation results and its disturbance rejection properties.

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Differential Filtering of Two Presynaptic Depression Mechanisms

Neural Computation ◽

10.1162/089976601300014637 ◽

2001 ◽

Vol 13 (1) ◽

pp. 69-85 ◽

Cited By ~ 12

Author(s):

Richard Bertram

Keyword(s):

G Protein ◽

High Frequency ◽

Computational Models ◽

Pass Filter ◽

Low Pass Filter ◽

Protein Inhibition ◽

Input Signals ◽

Low Pass ◽

High Pass ◽

Impulse Train

The filtering of input signals carried out at synapses is key to the information processing performed by networks of neurons. Two forms of presynaptic depression, vesicle depletion and G-protein inhibition of Ca2+ channels, can play important roles in the presynaptic processing of information. Using computational models, we demonstrate that these two forms of depression filter information in very different ways. G- protein inhibition acts as a high-pass filter, preferentially transmitting high-frequency input signals to the postsynaptic cell, while vesicle depletion acts as a low-pass filter. We examine how these forms of depression separately and together affect the steady-state postsynaptic responses to trains of stimuli over a range of frequencies. Finally, we demonstrate how differential filtering permits the multiplexing of information within a single impulse train.

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Sliding-Mode Observer for Speed and Position Sensorless Control of Linear-PMSM

Electrical Control and Communication Engineering ◽

10.2478/ecce-2014-0003 ◽

2014 ◽

Vol 5 (1) ◽

pp. 20-26 ◽

Cited By ~ 10

Author(s):

Saeed Masoumi Kazraji ◽

Ramin Bavili Soflayi ◽

Mohammad Bagher Bannae Sharifian

Keyword(s):

Sliding Mode ◽

Sensorless Control ◽

Sliding Mode Observer ◽

Phase Lag ◽

Sigmoid Function ◽

Pass Filter ◽

Low Pass Filter ◽

Chattering Phenomenon ◽

Low Pass ◽

Position Sensorless

Abstract The paper presents a sliding-mode observer that utilizes sigmoid function for speed and position sensorless control of permanent-magnet linear synchronous motor (PMLSM). In conventional sliding mode observer method there are the chattering phenomenon and the phase lag. Thus, in order to avoid the usage of the low pass filter and the phase compensator based on back EMF, in this paper a sliding mode observer with sigmoid function for detecting the back EMF in a PMLSM is designed to estimate the speed and the position of the rotor. Most of conventional sliding mode observers use sign or saturation functions which need low pass filter in order to detect back electromotive force (back EMF). In this paper a sigmoid function is used instead of discontinuous sign function to decrease undesirable chattering phenomenon. By reducing the chattering, detecting of the back EMF can be made directly from switching signal without any low pass filter. Thus the delay time in the proposed observer is eliminated because of the low pass filter. Furthermore, there is no need to compensate phase fault in position and speed estimating of linear-PMSM. Advantages of the proposed observer have been shown by simulation with MATLAB software.

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Theoretical and Experimental Study on Nonlinear Failure of an MEMS Accelerometer under Dual Frequency Acoustic Interference

Sensors ◽

10.3390/s21030945 ◽

2021 ◽

Vol 21 (3) ◽

pp. 945

Author(s):

Peng Guo ◽

Jiayu Zhang ◽

Lihui Feng ◽

Jianmin Cui ◽

Chaoyang Xing

Keyword(s):

Mathematical Model ◽

Damping Ratio ◽

Maximum Amplitude ◽

Dual Frequency ◽

Maximum Acceleration ◽

Pass Filter ◽

Low Pass Filter ◽

Low Pass ◽

The Mathematical Model ◽

Frequency Sweeping

In order to quantitatively study the interfered output of the accelerometer under an acoustic injection attack, a mathematical model for fitting and predicting the accelerometer output was proposed. With ADXL103 as an example, an acoustic injection attack experiment with amplitude sweeping and frequency sweeping was performed. In the mathematical model, the R-squared coefficient was R2 = 0.9990 in the acoustic injection attack experiment with amplitude sweeping, and R2 = 0.9888 with frequency sweeping. Based on the mathematical model, the dual frequency acoustic injection attack mode was proposed. The difference frequency signal caused by the nonlinear effect was not filtered by the low-pass filter. At a 115 dB sound pressure level, the maximum acceleration bias of the output was 4.4 m/s2 and the maximum amplitude of fluctuation was 4.97 m/s2. Two kinds of methods of prevention against acoustic injection attack were proposed, including changing the damping ratio of the accelerometer and adding a preposition low-pass filter.

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