Sinusoidal Modulation of the Parameter

2015 ◽  
pp. 125-152
Keyword(s):  
Sinusoidal Modulation

Visible Light Driven Degradation of Terephthalic Acid: Optimization of Energy Demand by Light Modulation Techniques

2020 ◽  
Vol 01 ◽  
Author(s):  
Diana Sannino ◽  
Vincenzo Vaiano ◽  
Olga Sacco ◽  
Nicola Morante ◽  
Luca De Guglielmo ◽  
...  
Keyword(s):  
Visible Light ◽  
White Light ◽  
Terephthalic Acid ◽  
Kinetic Constant ◽  
Fixed Bed ◽  
Light Modulation ◽  
Photocatalytic Reactor ◽  
Sinusoidal Modulation ◽  
Photocatalytic System ◽  
Modulation Techniques

Aims: The aim of this work was to investigate the impact of light modulation parameters on the degradation of terephtalic acid, an organic model pollutant, within a heterogeneous photocatalytic system under visible light. For this purpose, a fixed bed photocatalytic reactor, irradiated by white-light LEDs matrix controlled by a system for light dimming, was used. The bed consisted of a nitrogen-doped titania photocatalyst deposited on polystyrene pellets. Background: Wastewater containing TPA can be treated into conventional aerobic biological units. However, the mineralization of TPA is slow and inefficient and its presence influences negatively the biodegradation efficiency because this pollutant inhibits microbial growth. Nowadays innovative technologies named advanced oxidation processes (AOPs), such as heterogeneous photocatalysis with UV and visible light, ozonation, Fenton oxidation have gained popularity for effective organic destruction of TPA from wastewater. The heterogeneous photocatalytic oxidation process of the TPA under visible light is the most advantageous process in terms of both fixed and operating costs. Objective: In this work the successful application of light modulation techniques to degradation of TPA using a photocatalytic system with supported visible active photocatalysts (N-doped TiO2) immobilized on polystyrene pellets was reported. In particular, sinusoidal lighting has been used analyzing the influence of the period of oscillation and the amplitude of the light modulation on the reaction kinetics, in such a way as to minimize the times and energy costs for the process. Methods: To evaluate the influence of light modulation on the efficiency of the TPA removal, a discontinuous system composed by a Recirculating Photocatalytic Fixed Bed Reactor (RPFBR) irradiated by a matrix of white light LEDs was used. The flat geometry of photoreactor guarantees the efficient excitation of photocatalyst. An amount of 250 mL of aqueous solution with initial TPA concentration of 12.5 ppm was applied in the photocatalytic tests lasting 180 min of irradiation fixed or sinusoidal modulated. Results: The results show that the variation of the oscillation period of the sinusoidal modulation has a relevant influence on the photodegradation of TPA and a maximum value of the apparent kinetic constant, 0.0045 min-1 is found when the period of oscillation is 0.24 s. The sinusoidal modulation with optimal amplitude is that with current between 50-200 mA, that shows the highest value of the apparent kinetic constant, equal to 0.0046 min-1. The optimal sinusoidal modulation, as a consequence is with current between 50-200 mA and period of 0.24 s. From the data collected from the tests, it is possible to evaluate the energy cost necessary to obtain the reduction of 90% of the terephthalic acid in 1 m3 of polluted water for each modulation (E E/O ), and compare these values with other tests for TPA degradation reported in the literature. The internal comparison and with the three systems of literature showed the optima sinusoidal modulation of LEDs matrix permits a strong reduction the electrical energy consumption. Conclusion: Photocatalytic tests have demonstrated the improvement of the process energy efficiency using the light modulation technique . A further confirmation of the advantage of light modulation was obtained by comparing the energy costs required for the abatement of 90% of the terephthalic acid in 1m 3 of the photocatalytic system. Finally, a mathematical model for photocatalytic degradation of terephthalic acid within the recirculating fixed bed photocatalytic reactor, irradiated by white-light LEDs was developed.

scholarly journals Equilibration of sinusoidal modulation of temperature in linear and nonlinear chains

2020 ◽  
Vol 102 (6) ◽  
Author(s):  
Elena A. Korznikova ◽  
Vitaly A. Kuzkin ◽  
Anton M. Krivtsov ◽  
Daxing Xiong ◽  
Vakhid A. Gani ◽  
...  
Keyword(s):  
Sinusoidal Modulation ◽  
Linear And Nonlinear

Experimental Techniques for Controlling Chaos in Lasers

1998 ◽  
Vol 08 (09) ◽  
pp. 1759-1768 ◽  
Author(s):  
R. Meucci ◽  
A. Labate ◽  
M. Ciofini
Keyword(s):  
Power Spectrum ◽  
Chaotic Dynamics ◽  
Feedback Loop ◽  
Control Parameter ◽  
Experimental Techniques ◽  
Controlling Chaos ◽  
Sinusoidal Modulation ◽  
Control Schemes ◽  
Frequency Components

This paper presents two control schemes for the chaotic dynamics of CO 2 laser with feedback which can be applied after the recognition of a leading frequency of the motion in the power spectrum. The first one is realized by means of a selective feedback loop which rejects all the frequency components except that of the leading cycle to be stabilized. The second one consists in a resonant sinusoidal modulation of the control parameter.

Piezoelectric Material Electrostriction Coefficient Measurement Method Combined Sinusoidal Modulation with Multi-beam Laser Heterodyne

2017 ◽  
Vol 38 (12) ◽  
pp. 1661-1667
Author(s):  
甄佳奇 ZHEN Jia-qi ◽  
仲维丹 ZHONG Wei-dan ◽  
布音嘎日迪 BU Yingaridi ◽  
高亚臣 GAO Ya-chen ◽  
刘 勇 LIU Yong ◽  
...  
Keyword(s):  
Piezoelectric Material ◽  
Measurement Method ◽  
Sinusoidal Modulation ◽  
Beam Laser ◽  
Laser Heterodyne ◽  
Coefficient Measurement

Multiple-Frequency Nanoindentation Testing

2004 ◽  
Vol 841 ◽  
Author(s):  
A. C. Fischer-Cripps
Keyword(s):  
Mechanical Properties ◽  
Transfer Function ◽  
Frequency Modulation ◽  
Driving Force ◽  
Multiple Frequency ◽  
Sinusoidal Modulation ◽  
Nanoindentation Testing ◽  
Instrument Response ◽  
Force Signal ◽  
Dynamic Nanoindentation

ABSTRACTThis paper describes a new method of dynamic nanoindentation testing whereby, instead of the imposition of a single sinusoidal modulation onto the driving force signal, a multiple-frequency modulation is applied and a Fourier analysis used to extract frequency-dependent mechanical properties. The instrument response is cancelled by the use of a reference transfer function using an equalization process. The present work gives details of the method and presents some example measurements.

An Additional Dimension to Grating Perception

Perception ◽  
1978 ◽  
Vol 7 (6) ◽  
pp. 707-715
Author(s):  
Christopher W Tyler
Keyword(s):  
Visual Acuity ◽  
Spatial Frequency ◽  
Modulation Frequency ◽  
Two Dimensional ◽  
Sinusoidal Modulation ◽  
Additional Dimension ◽  
Harmonic Components ◽  
Perceptual Mechanism

Visual acuity ( A) for a two-dimensional multiplicative sinusoidal contrast grid (sinusoidal chessboard) was measured as a function of spatial frequency (ω) of modulation in one of the dimensions. The reduction in acuity as frequency was increased was well described by the equation: A = −2 πkω + c, where k and c are constants. At suprathreshold contrasts, the frequency of modulation appeared to be doubled relative to the underlying modulation frequency. This doubling is not related to the frequency of the harmonic components of the chessboard, but suggests the existence of a perceptual mechanism sensitive to areas of sinusoidal modulation which are seen at twice the frequency of the variation in contrast.

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