Guest Lecture

MS Teams Meeting

Among the promising technologies of the fourth industrial revolution, additive manufacturing (AM) is considered as a key factor for the success of the new production standard. However, a lack of assurance of quality with AM parts is a key technological barrier that prevents manufacturers from adopting AM technologies, especially for high-value applications where component failure cannot be tolerated. Developments in process control have allowed the significant enhancement of AM techniques and marked improvements in surface roughness and material properties, along with a reduction in inter-build variation and the occurrence of embedded material discontinuities, hence the exploitation of AM processes continues to accelerate. Though still in the emergent stages, process monitoring is beginning to see strong adoption in the additive manufacturing community through the use of process sensors recording a wide range of optical, acoustic, and thermal signals. The ability to acquire these signals in a holistic manner, coupled with artificial intelligence (AI) based machine control has the potential to make additive manufacturing a robust and competitive alternative to conventional fabrication techniques

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A semiconductor laser with optical feedback is a paradigm for studying nonlinear dynamics in delayed feedback systems and has been intensely investigated in recent years. At a fundamental level, these investigations are an ideal test bed for laboratory studies of time-delayed systems. At an applied level, some of the dynamical behaviors that arise in these systems have been exploited for cryptography, and random number generation, among others. In this talk, I will give an overview of the dynamical behaviors that arise in semiconductor lasers due to various types of optical feedback, and experimental strategies for controlling the laser intensity and optical frequency dynamics. Time permitting, I will conclude with recent work on laboratory realizations of effective non-Hermitian Hamiltonians in time-delay coupled semiconductor lasers.

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Fe-based bulk metallic glasses (BMGs) have gained considerable interest due to their excellent soft magnetic properties with high saturation magnetization, high electrical resistivity, very good corrosion resistance, low materials cost, extremely high mechanical strength, and hardness. In spite of having excellent magnetic properties, Fe-based BMGs are not used as engineering materials in service, so far. The major obstacle is their inherent brittleness under mechanical loading, once a crack is developed the material fails catastrophically. Owing to the ever-growing industrial demand for materials with outstanding properties, aside from exploring new alloy compositions, it is pertinent to understand why or why-not the existing system work and how to improve their properties. In this work I have attempted to understand the basics behind improving the room temperature plastic deformability in Fe36Co36B19.2Si4.8Nb4 and Fe74Mo4P10C7.5B2.5Si2 ferromagnetic BMGs. Addition of small at.% Ga proved to be a viable solution to improve the plastic deformability in the ferromagnetic Fe-based metallic glasses without compromising on thermal and magnetic properties of the glass. I have also attempted to gain basic knowledge in casting the Fe-based BMG on an industrial scale. My effort was tremendously successful; I was able to produce fully amorphous complex-shaped samples with the excellent surface finish.