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- anharmonic Bloch oscillations
- coupled mode method
- array of waveguides
- active harmonic filter
- Multifunctional VSC
- unity power factor operation
- power quality improvement
- grid-connected SPV system
- renewable energy sources
- Optoelectronic Information Science and Engineering
- Electrical Engineering and Automation
- Shevchenko Pridnestrovskii State University
- Malaviya National Institute of Technology
- Academy of Sciences of Moldova
- IIITD&M Kancheepuram
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[IEEE 2019 International Conference on Intelligent Computing and Control Systems (ICCS) - Madurai, India (2019.5.15-2019.5.17)] 2019 International Conference on Intelligent Computing and Control Systems (ICCS) - Controlled PV Systems Power Quality Retention and Output Power Escalation
摘要： Due to the burden on fossil fuels the trend of generating power through renewable energy resources is gaining more importance day by day. In such systems there are issues related to efficiency and reliability. The paper focuses mainly on developing a model using MATLAB / SIMULINK software to overcome the above mentioned obstacles to the PV system and improve its overall performance by introducing appropriate control schemes. The aim of the PV system design is to escalate the output power under varying environmental conditions and also to retain the power quality of the PV system during faulty conditions. MPPT is applied to optimize through Incremental conductance thus ensuring the system is running at its maximum power point irrespective of the partial shading effect and temperature variations in the environment. With the employment of power quality compensation scheme that in turn uses a DVR, the system is capable of restoring the power quality thereby commuting the power quality issues. Significant fall in the THD levels is attained by usage of DVR control scheme along with a CHB multilevel DC/AC converter. The significance of developing MPPT algorithm is illustrated by examining the impact of partial shading condition and the temperature variations on its productivity. The demonstration of the power quality compensation capability of the PV system is achieved by the power quality compensation control scheme under faulty conditions.
关键词： Cascaded H-Bridge Multilevel Inverter (CHB),Incremental Conductance (IncCond),Total Harmonic Distortion (THD),Dynamic Voltage Restorer (DVR),Maximum Power Point Tracking (MPPT)
更新于2025-09-23 15:21:01
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[ASME ASME 2018 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference - Quebec City, Quebec, Canada (Sunday 26 August 2018)] Volume 8: 30th Conference on Mechanical Vibration and Noise - Piezoelectric Nonlinear Energy Sink for Energy Harvesting With Rectifying DC Interface Circuit
摘要： In order to improve the performance of vibration energy harvesters over a broad frequency range, this paper proposes a use of piezoelectric nonlinear energy sink (NES) for energy harvesting from ambient vibrations. A standard rectifying direct current (DC) interface circuit is considered to generate DC power from the piezoelectric NES under harmonic excitation. Harmonic balance method is used to obtain the dynamic response and energy harvesting performance of the proposed piezoelectric NES, verified by the equivalent circuit simulation. Analytical and numerical results show that the design, by applying NES, improves the efficiency of energy harvesting without increasing the vibration of the primary structure in a broadband manner. The effects of the electromechanical coupling, excitation level and load resistance on the magnitude and bandwidth of the output DC power are investigated.
关键词： harmonic excitation,rectifying DC interface circuit,piezoelectric,energy harvesting,nonlinear energy sink
更新于2025-09-23 15:21:01
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Diode pumped Nd:YVO <sub/>4</sub> /LBO/Ba(NO <sub/>3</sub> ) <sub/>2</sub> Raman laser at 563 nm
摘要： Radiation at a wavelength of 563 nm was achieved using an all-solid-state laser system based on a diode-pumped actively Q-switched Nd3+:YVO4 laser with intra-cavity second harmonic generation in LBO followed by intra-cavity Raman conversion in Ba(NO3)2. The output power of 101 mW was achieved under a pump power of 5 W and a modulation frequency of 12.7 kHz with a slope conversion efficiency of 19%. The achieved peak power at 563 nm was 0.67 kW, which allows one to use this laser in medical treatment through selective excitation of deoxyhemoglobin into its long-wavelength absorption peak.
关键词： stimulated Raman scattering,intracavity second harmonic generation,563 nm,Raman laser
更新于2025-09-23 15:21:01
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Infrared Camera-Based Non-contact Measurement of Brain Activity From Pupillary Rhythms
摘要： Pupillary responses are associated with affective processing, cognitive function, perception, memory, attention, and other brain activities involving neural pathways. The present study aimed to develop a noncontact system to measure brain activity based on pupillary rhythms using an infra-red web camera. Electroencephalogram (EEG) signals and pupil imaging of 70 undergraduate volunteers (35 female, 35 male) were measured in response to sound stimuli designed to evoke arousal, relaxation, happiness, sadness, or neutral responses. This study successfully developed a real-time system that could detect an EEG spectral index (relative power: low beta in FP1; mid beta in FP1; SMR in FP1; beta in F3; high beta in F8; gamma P4; mu in C4) from pupillary rhythms using the synchronization phenomenon in harmonic frequency (1/100 f) between the pupil and brain oscillations. This method was effective in measuring and evaluating brain activity using a simple, low-cost, noncontact system, and may be an alternative to previous methods used to evaluate brain activity.
关键词： harmonic frequency,pupil size variation,brain activity,vital sign monitoring,non-contact measurement
更新于2025-09-23 15:21:01
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Structure gauges and laser gauges for the semiconductor Bloch equations in high-order harmonic generation in solids
摘要： The semiconductor Bloch equations (SBEs) are routinely used for simulations of strong-field laser-matter interactions in condensed matter. In systems without inversion or time-reversal symmetries, the Berry connections and transition dipole phases (TDPs) must be included in the SBEs, which in turn requires the construction of a smooth and periodic structure gauge for the Bloch states. Here, we illustrate a general approach for such a structure-gauge construction for topologically trivial systems. Furthermore, we investigate the SBEs in the length and velocity gauges and discuss their respective advantages and shortcomings for the high-harmonic generation (HHG) process. We find that in cases where we require dephasing or separation of the currents into interband and intraband contributions, the length-gauge SBEs are computationally more efficient. In calculations without dephasing and where only the total current is needed, the velocity-gauge SBEs are structure-gauge independent and are computationally more efficient. We employ two systems as numerical examples to highlight our findings: a one-dimensional model of ZnO and the two-dimensional monolayer hexagonal boron nitride (hBN). The omittance of Berry connections or TDPs in the SBEs for hBN results in nonphysical HHG spectra. The structure- and laser-gauge considerations in the current work are not restricted to the HHG process and are applicable to all strong-field matter simulations with SBEs.
关键词： laser gauge,Berry connections,transition dipole phases,high-harmonic generation,semiconductor Bloch equations,structure gauge
更新于2025-09-23 15:21:01
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Nonlinear Optics || The Nonlinear Optical Susceptibility
摘要： Nonlinear optics is the study of phenomena that occur as a consequence of the modification of the optical properties of a material system by the presence of light. Typically, only laser light is sufficiently intense to modify the optical properties of a material system in this manner. The beginning of the field of nonlinear optics is often taken to be the discovery of second-harmonic generation by Franken et al. (1961), shortly after the demonstration of the first working laser by Maiman in 1960. Nonlinear optical phenomena are "nonlinear" in the sense that they occur when the response of a material system to an applied optical field depends in a nonlinear manner on the strength of the applied optical field. For example, second-harmonic generation occurs as a result of the part of the atomic response that scales quadratically with the strength of the applied optical field. Consequently, the intensity of the light generated at the second-harmonic frequency tends to increase as the square of the intensity of the applied laser light.
关键词： Material system,Optical properties,Nonlinear optics,Laser light,Second-harmonic generation
更新于2025-09-23 15:21:01
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Nonlinear Optics || Quantum-Mechanical Theory of the Nonlinear Optical Susceptibility
摘要： In this chapter, we use the laws of quantum mechanics to derive explicit expressions for the nonlinear optical susceptibility. The motivation for obtaining these expressions is at least three-fold: (1) these expressions display the functional form of the nonlinear optical susceptibility and hence show how the susceptibility depends on material parameters such as dipole transition moments and atomic energy levels, (2) these expressions display the internal symmetries of the susceptibility, and (3) these expressions can be used to make predictions of the numerical values of the nonlinear susceptibilities. These numerical predictions are particularly reliable for the case of atomic vapors, because the atomic parameters (such as atomic energy levels and dipole transition moments) that appear in the quantum-mechanical expressions are often known with high accuracy. In addition, since the energy levels of free atoms are very sharp (as opposed to the case of most solids, where allowed energies have the form of broad bands), it is possible to obtain very large values of the nonlinear susceptibility through the technique of resonance enhancement. The idea behind resonance enhancement of the nonlinear optical susceptibility is shown schematically in Fig. 3.1.1 for the case of third-harmonic generation. In part (a) of this figure, we show the process of third-harmonic generation in terms of the virtual levels introduced in Chapter 1. In part (b) we also show real atomic levels, indicated by solid horizontal lines. If one of the real atomic levels is nearly coincident with one of the virtual levels of the indicated process, the coupling between the radiation and the atom becomes particularly strong and the nonlinear optical susceptibility becomes large.
关键词： resonance enhancement,quantum mechanics,nonlinear optical susceptibility,third-harmonic generation,dipole transition moments,atomic energy levels
更新于2025-09-23 15:21:01
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Harmonic detection method based on adaptive noise cancellation and its application in photovoltaic - active power filter system
摘要： The adaptive harmonic detection method based on the adaptive noise cancellation principle has the advantages of strong adaptability and good robustness. However, when the step size of the algorithm is selected, there is a conflict between the convergence speed and the steady-state accuracy. To solve this problem, this paper proposes an improved variable step size adaptive harmonic detection method. The algorithm uses the sliding integrator to find the feedback that can truly reflect the tracking situation, and substitutes it into the step size iteration formula based on L2 norm to achieve the step size adjustment. In order to further verify the superiority and practicability of the improved algorithm, the algorithm is applied to the photovoltaic-active power filter (PV-APF) system, and simulation verification is performed in MATLAB. The simulation results show that under the same simulation conditions, the convergence speed of the improved algorithm is half a cycle faster than that of the traditional method, and the steady-state error is smaller. In the application of PV-APF system, under normal light, the dual functions of grid-connected photovoltaic system and harmonic compensation are realized. The total harmonic distortion (THD) of the system is 2.09%, which effectively improves the power quality of photovoltaic system.
关键词： Photovoltaic grid-connected,Adaptive noise cancellation,Harmonic detection,Active power filter,Photovoltaic-active power filter system
更新于2025-09-23 15:21:01
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Second harmonic generation at 544a??nm of a femtosecond laser
摘要： We study second harmonic generation (SHG) at 544 nm of the 0-type (e + e - e) quasi-phase-matching based on a femtosecond laser at 1088 nm. The green pulse with the spectrum width of 0.6 nm and the peak power of 17.7 kW is obtained at the pump power density of 2.81 GW/cm2 and the conversion e?ciency is 21 %. As the propagation distance along the PPMgLN crystal increases, the spectrum at 544 nm becomes narrower and narrower and the pulse duration broadens very seriously.
关键词： Group velocity match,544 nm laser,Second harmonic generation,PPMgLN,Ultrafast optics,Femtosecond pulses
更新于2025-09-23 15:21:01
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Analyzing role of relaxation time on second harmonic generation and optical dielectric function of impurity doped quantum dots under the aegis of noise
摘要： Present study monitors the influence of relaxation time (τ) on second harmonic generation (SHG) and total optical dielectric function (TODF) of impurity containing quantum dot (QD) under the stewardship of Gaussian white noise. Two distinct roadways viz. ‘additive’ and ‘multiplicative’ have been exploited for the entrance of noise to the system. Both in absence and presence of noise the SHG and TODF peak positions do not exhibit any shift with increase in τ. The SHG peak values display monotonic behavior with the variation of τ. However, the TODF peak values delicately depend on variation of τ being guided by the presence of noise and also on its mode of introduction. Presence of additive (multiplicative) noise causes enhancement (suppression) of SHG and TODF peak values as τ varies over a range. The findings appear to be crucial in the fabrication of QD-based opto-electronic devices where role of noise deserves to be properly addressed.
关键词： Quantum dot,Gaussian white noise,Impurity,Total optical dielectric function,Relaxation time,Second harmonic generation
更新于2025-09-23 15:21:01