Publications

Finding a simple path of even length between two designated vertices in a directed graph is a fundamental NP-complete problem [24] known as the EvenPath problem. Nedev [28] proved in 1999, that for directed planar graphs, the problem can be solved in polynomial time. More than two decades since then, we make the first progress in extending the tractable classes of graphs for this problem. We give a polynomial time algorithm to solve the EvenPath problem for classes of H-minor-free directed graphs,1 where H is a single-crossing graph. We make two new technical contributions along the way, that might be of independent interest. The first, and perhaps our main, contribution is the construction of small, planar, parity-mimicking networks. These are graphs that mimic parities of all possible paths between a designated set of terminals of the original graph. Finding vertex disjoint paths between given source-destination pairs of vertices is another fundamental problem, known to be NP-complete in directed graphs [14], though known to be tractable in planar directed graphs [34]. We encounter a natural variant of this problem, that of finding disjoint paths between given pairs of vertices, but with constraints on parity of the total length of paths. The other significant contribution of our paper is to give a polynomial time algorithm for the 3-disjoint paths with total parity problem, in directed planar graphs with some restrictions (and also in directed graphs of bounded treewidth).

Shrinking of the thickness of silicon on insulator (SOI) has been proposed as a potential solution for scaling down the physical base length of symmetric lateral electrostatically doped bipolar transistors. An ultra-thin body device that utilizes the full SOI thickness has been presented and the performance of the same is investigated in detail. The device features two distinct doping techniques: work function-induced electrostatic doping (WED) and bias-induced electrostatic doping (BED). The proposed design approach leads to significant improvements in gain and cut-off frequency compared to previously reported designs. The resulting devices exhibit peak current gain β values >1100, ft>500 GHz, fmax>1300 GHz. Moreover, these improved device performance matrices get translated into better performance of universal gates with low rise and fall time of ∼1.3 ns, and improved noise margin performance in static random access memory (SRAM) device of 0.43 and 0.41 for WED and BED based devices respectively. Furthermore, the study investigates the reliability of the device concerning breakdown voltage and its response to different temperature conditions. The findings reveal a decline in the β value for WED-based devices when subjected to temperatures exceeding 340 K. In contrast, BED-based devices demonstrate a comparatively smaller variation in β at temperatures above 340 K. These results show the potential of the proposed device for mixed-signal and digital circuit applications.

In this study it was determined the impact of calcination or mechano-chemical activation (MCA) on the physico-chemical properties and reactivity of Ca-montmorillonite and Na-montmorillonite clays, and its subsequent effect on phase assemblage evolution of sodium hydroxide activated cements. MCA enabled colour control, enhanced early age reactivity of montmorillonite clays, associated with dehydroxylation and amorphization of the treated clay, while inducing spheroidal particle morphologies and reduced external surface area. These factors led to an accelerated onset of the polycondensation reaction, as well as an enhanced workability of alkali-activated pastes produced with them, compared with pastes produced with calcined clays. Independent of the clay treatment, a sodium aluminosilicate hydrate (N-A-S-H) alongside zeolitic reaction products were identified. This study demonstrates that MCA is an effective route to enhance reactivity of montmorillonites, resolving some challenges when using calcined clays for producing alkali-activated cements.

Aging, marked by dysregulated cellular systems, gives rise to a spectrum of age-related disorders, including neurodegeneration, atherosclerosis, immunosenescence, and musculoskeletal issues. These conditions contribute significantly to the global disease burden, posing challenges to health span and economic resources. Current therapeutic approaches, although diverse in mechanism, often fall short in targeting the underlying cellular pathologies. They fail to address the issues compounded by altered pharmacokinetics in the elderly. Nanotechnology emerges as a transformative solution, offering tissue-specific targeted therapies through nanoparticles. Functional nanomaterials (FNMs) respond to internal or external stimuli, with light-responsive nanomaterials gaining prominence. Harnessing the benefits of deep tissue penetration and ease of manipulation particularly in the near-infrared spectrum, light-responsive FNMs present innovative strategies for age-related comorbidities. This review comprehensively summarizes the potential of light-responsive FNM-based approaches for targeting cellular environments in age-related disorders, and also emphasizes the advantages over traditional treatment modalities. Specifically, it focuses on the development of various classes of light-responsive functional nanomaterials including plasmonic nanomaterials, nanomaterials as carriers, upconversion nanomaterials, 2D nanomaterials, transition metal oxide and dichalcogenide nanomaterials and carbon-based nanomaterials against age related diseases. We foresee that such advanced developments in the field of nanotechnology could provide a new hope for clinical diagnosis and treatment of age-related disorders.

To overcome the limitations of the Fourier nonlinear filter and even mirror Fourier nonlinear filter-based adaptive algorithms for active noise control, this paper introduces boosted Fourier nonlinear filter and boosted even mirror Fourier nonlinear filter algorithms. Weight updating equations for the proposed algorithms are derived. Their performance is compared with Fourier nonlinear filter and even mirror Fourier nonlinear filter. Experimentally recorded bandsaw and compressor noises are utilized for the analysis. The analysis is carried out for (a) linear primary and linear secondary paths, and (b) nonlinear primary path and linear secondary path. Visual inspection of residual noises after control and dB values of residual noises are utilized to understand the performance of the developed algorithms.