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Fault-Tolerant Control of Active Power Filter With Balanced Three-Phase Line Currents
No full textTransformer isolated three-phase three-wire two-level active power filters (APF) using pulse width modulated (PWM) control are widely used for shunt compensation of harmonic currents. In a situation when only two of the converter legs remain connected to the grid due to an open circuit fault in one of the converter legs or its internal lines or in one of its line reactors, the existing fault-tolerant schemes cannot continue operation with balanced grid side line currents, resulting in improper harmonic compensation. A new control scheme is proposed in this article by which APF can seamlessly continue fault-tolerant operation during single line open-circuit fault and inject balanced three-phase harmonic currents into the line for proper compensation, without requiring any redundant legs or switches to change the internal power configuration. Unlike conventional APF schemes, a simple control scheme is proposed to adjust the phase shift between the composite harmonic currents in the two operative legs of the converter connected to the grid via a full rated delta/star isolation transformer (or an existing delta-star distribution transformer) with neutral connected to dc bus midpoint to inject balanced harmonic currents into the grid. Simulation and experimental results are provided to validate the effectiveness of proposed concept
Structure–property predictions in metallic glasses: Insights from data-driven atomistic simulations
No full textThe field of metallic glasses has been an active area of research owing to the complex structure–property correlations and intricacies surrounding glass formation and relaxation. This review provides a thorough examination of significant works that elucidate the structure–property correlations of metallic glasses, derived from detailed atomistic simulations coupled with data-driven approaches. The review starts with the theoretical and fundamental framework for understanding important properties of metallic glasses such as transition temperatures, relaxation phenomena, the potential energy landscape, structural features such as soft spots and shear transformation zones, atomic stiffness and structural correlations. The need to understand these concepts for leveraging metallic glasses for a wide range of applications such as performance under tensile loading, viscoelastic properties, relaxation behavior and shock loading is also elucidated. Finally, the use of machine learning algorithms in predicting the properties of metallic glasses along with their applications, limitations and scope for future work is presented
Upcycling Fruit Waste: A Sustainable Route to Nanoparticles Synthesis and Applications
No full textFruits are a common part of a healthy human diet as they are rich in vitamins, minerals, antioxidants, dietary fibers, and flavor. However, the processing and subsequent consumption of fruits result in a significant amount of waste. The waste, including peels, seeds, and pulp, is often discarded, despite being abundant in valuable bioactive compounds. Moreover, the increasing social, economic, and environmental burden due to food waste is of critical concern, especially in poor and developing countries. Hence, the effective repurposing of food waste into beneficial products is of critical importance. One promising approach is the green synthesis of biomaterials such as nanoparticles for various biological, environmental, and agricultural applications. This review emphasizes the utilization of bioactive compounds obtained from different fruit waste byproducts for the green synthesis of nanoparticles and aims to provide a comprehensive understanding of waste valorization through green nanotechnology and sustainability
Structural insights into the recognition of RALF peptides by FERONIA receptor kinase during Brassicaceae pollination
No full textField redefinition and its impact in relativistic hydrodynamics
No full textIn this paper, we explore the impact of field redefinition on the spectrum of linearized perturbations in relativistic hydrodynamics. We observe that the spectrum of hydrodynamics modes is never affected by the local field redefinition, however, the spectrum of the nonhydrodynamic modes is affected. Through an appropriate all-order redefinition, nonhydrodynamic modes can be eliminated, leading to a new frame where the spectrum contains only hydrodynamic modes. We also observe that the resulting stress-energy tensor may have an infinite series in momentum space, with a convergence radius linked to the eliminated nonhydrodynamic mode. In certain special cases, higher-order terms in the stress-energy tensor under field redefinition may cancel, indicating that nonhydrodynamic modes are mere artifacts of the fluid variable choice and hold no physical significance, even if they appear to violate physical constraints. Using a special toy example, we find a criterion to distinguish between physical and unphysical nonhydrodynamic modes
Optimized Random Features for the Neural Tangent Kernel
No full textThe neural tangent kernel (NTK) has emerged as an important tool in recent years, both for developing a theoretical understanding of deep learning as well as for various applications. Even though recursive closed form expressions have been derived for computing the NTK, these become computationally expensive as the complexity of a network increases. Recent papers have looked at reducing this complexity using various sketching techniques along with random features. Building on these techniques, we propose an additional optimization step which results in better approximation of the NTK
Make metal–organic frameworks safe and sustainable by design for industrial translation
No full textMetal–organic frameworks hold immense application potential, but their stability and environmental safety remain barriers to industrial translation. Embracing the ‘safe and sustainable by design’ framework would, however, set a transformative pathway to the development of robust, recyclable metal–organic frameworks, ensuring functionality, minimal ecological impact and alignment with circular economy and chemical sustainability goals
Harnessing self-powered and photoresponsive biomechanical activity sensors by exploring the piezo-phototronic effect in lead-free layered halide perovskite/PVDF composites
No full textDeveloping flexible, wearable, efficient, and self-powered electronic devices based on piezoelectric nanogenerators aspires to be a sustainable solution to renewable energy harvesting and storage. We report on a lead-free halide perovskite Cs3Sb2I9 and polyvinylidene fluoride (PVDF) based composite device capable of scavenging energy from routine biomechanical activities. Regulated incorporation and optimization of Cs3Sb2I9 into the PVDF matrix increased the electroactive phase of the device to ~82% with a piezoelectric coefficient of 7.48 pm V-1. The champion device produced an open circuit output voltage of 85 V and a current of 2.6 µA. Furthermore, the device generated approximately ~1.26 µW cm-2 of power density when connected to a 0.8 MO resistor, sufficient to operate portable electronic gadgets. We tested the device for its energy generation capabilities under simple human biomechanical movements such as hand hammering, finger tapping, elbow bending, knee bending, and toe pressing. To demonstrate the versatility of the nanogenerator device, we also tested its energy generation and storage capabilities by charging capacitors up to ~2.2 V. The device exhibited impressive durability and repeatability over 10 000 cycles, underscoring its potential as a promising solution for addressing the energy demand of portable and Internet of Things (IoT) devices through piezoelectric nanogenerators. Work function calculations using density functional theory demonstrated that the composite exhibited a reduced work function compared to individual components, indicating favorable electron emission characteristics. We also realized the piezo-phototronic effect in the composite using a self-powered photodetector, which exhibited an increment of 63% in the photocurrent, offering potential for piezotronic and optoelectronic devices
