Multi scale hierarchical structures underpin mechanical, optical, and wettability behavior in nature. Here we present a novel approach which can be used to mimic the natural hierarchical patterns in a quick and easy maskless fabrication. By using two‐beam interference lithography with angle‐multiplexed exposures and scanning, we have successfully printed large‐area complex structures having a cascading resolution and 3D surface profiles. By precisely controlling the exposure dose we have demonstrated a capability to create different 3D textured surfaces having comparable aspect ratio with period spanning from 4 μm to 300 nm (more than one order of magnitude) and the height spanning from 0.9 μm to 40 nm, respectively. Up to three levels of biomimetic hierarchical structures were obtained that show several natural phenomena: superhydrophobicity, iridescence, directionality of reflectivity, and polarization at different colors.

This paper analyzes the impact of remote classrooms and labs as an outcome of “social distancing” during COVID-19 outbreak. It is important to analyze the emergence of web technologies and tools available for online learning and its impact on engineering education. The intended focus is to find a way out to address the issues regarding continued teaching and learning during long academic breaks due to this unpredicted pandemic. Some challenges in developing economies include the unavailability of internet services all over the country and limited resources accessible to large community to earn and learn during such epidemics. This study outlines various policy guidelines for online delivery of engineering courses and assessment techniques as experienced during this global pandemic. These guidelines will provide a roadmap for quality teaching and evaluation of online engineering courses.

In this paper, a nonlinear least squares optimization method is employed to optimize the performance of pole-zero-cancellation (PZC)-based digital controllers applied to a switching converter. An extensively used step-down converter operating at 1000 kHz is considered as a plant. In the PZC technique, the adverse effect of the (unwanted) poles of the buck converter power stage is diminished by the complex or real zeros of the compensator. Various combinations of the placement of the compensator zeros and poles can be considered. The compensator zeros and poles are nominally/roughly placed while attempting to cancel the converter poles. Although PZC techniques exhibit satisfactory performance to some extent, there is still room for improvement of the controller performance by readjusting its poles and zeros. The (nominal) digital controller coefficients thus obtained through PZC techniques are retuned intelligently through a nonlinear least squares (NLS) method using the Levenberg-Marquardt (LM) algorithm to ameliorate the static and dynamic performance while minimizing the sum of squares of the error in a quicker way. Effects of nonlinear components such as delay, ADC/DAC quantization error, and so forth contained in the digital control loop on performance and loop stability are also investigated. In order to validate the effectiveness of the optimized PZC techniques and show their supremacy over the traditional PZC techniques and the ones optimized by genetic algorithms (GAs), simulation results based on a MATLAB/Simulink environment are provided. For experimental validation, rapid hardware-in-the-loop (HiL) implementation of the compensated buck converter system is also performed.

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Formation of ripples by ablation of surfaces of laser-irradiated materials is an example of ultrafast energy delivery. Herein, we report on fs-laser optical imprinting of periodic nano-grooves on silica substrate at only 25% of the laser ablation threshold via an interface plasmonic light localization at the ZnS film (top) interface with silica (bottom) by plasmonic surface wave. The nano-grooves were formed throughout ZnS with the same period and orientation imprinted onto the underlying silica. Based on a detailed account of the multi-photon and avalanche ionization using the Drude model, laser-induced plasmonic ablation describes quantitatively the energy deposition from the top ZnS to the substrate of silica.

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This paper deals with lab design tools and their impact on the learning progression of firstyear electrical engineering students. Project-based learning is an innovative domain of acquiring knowledge in engineering education, where the role of experimental setup and use of advanced technology imitates real-world engineering problems. This experimentation induces a desire to learn in newly inducted students and influences their minds to understand the applied content of engineering education thus resulting in improved retention rates in engineering programs. A Likert scale is used to generate statistics which suggest that an intelligent design of engineering lab by choosing advanced learning methodology for freshmen electrical engineering students improves their ability to absorb modern engineering concepts as compared to the classical lab setup.