Indian Institute of Technology Madras

The first part of this two-article series described the continuous-time pipelined (CTP) ADC, which is appropriate when the oversampling ratio (OSR) is small. When the OSR is large, it becomes feasible to embed the quantizer into the antialias filter’s feedback loop. Such sub-systems are referred to as continuous-time delta-sigma modulators. This article describes the ideas behind such analog-to-digital converters.

Conservative discretizations of transport equations are based on integral formulations that include the finite volume method (FVM) and conservative finite difference methods (CFDMs). The FVM is used by most fluid dynamics simulation packages and requires smoothly shifting grids for better convergence. This motivates the study of the order of accuracy and rate of convergence of the FVM on non-uniform grids. It is difficult to do such an analysis of the FVM on an unstructured grid; however, the FVM is reduced to a CFDM on a Cartesian grid. The effect of the order of accuracy and the rate of convergence of higher-order CFDMs on arbitrarily varying grids are investigated. It is shown that higher-order conservative discretizations on arbitrarily varying non-uniform grids need some smoothness in the grid transition to be first-order accurate. The condition to achieve first-order accuracy is also presented. If the grid is replaced by a gradually varying grid, it is shown that conservative discretizations yield a better rate of convergence. In this situation, a rate of convergence between one and the theoretical maximum can be achieved in dependence on the grid stretch/contraction ratio. Numerical examples, including the linear convection-diffusion equation, the lid-driven cavity problem, and the Taylor-Green vortex problem, are presented.

A pair of comparable sized C‐shaped bis‐monodentate ligands (L1 and L2²⁺) and a linear bis‐monodentate ligand (L3) complementing to the terminal‐lengths of the C‐shaped ligands have been identified. One‐pot combination of cis‐Pd(tmeda)²⁺, L1 and L3 (2 : 1 : 1 ratio) in water resulted an octa‐cationic 2‐catenane, [Pd2(tmeda)2(L1)(L3)]2⁸⁺ in which two identical tetra‐cationic macromonocyclic coordination rings are interlocked; however, a guest bound coordination ring was formed in presence of a selected di‐anionic guest. Complexation of cis‐Pd(tmeda)²⁺ with a mixture of L2²⁺ and L3 (2 : 1 : 1 ratio) in water resulted the hexa‐cationic macromonocyclic coordination ring, [Pd2(tmeda)2(L2)(L3)]⁶⁺ whereas a guest bound coordination ring was formed in the presence of the di‐anionic guest. Addition of the guest to the preformed octa‐cationic catenane caused ring separation to favour the guest‐bound ring. This guest bound ring could be reverted to the 2‐catenane by sequestering the bound guest using the relatively electron deficient hexa‐cationic coordination ring. Thus, a design principle for reversible switching between a 2‐catenane and the constituent macromonocyclic‐rings using anion‐binding/‐sequestering as the core concept has been established.

Heliostats are devices used for solar concentration that use mirrors oriented according to the position of the sun. A heliostat's main function is to redirect sunlight for use in a variety of applications, including heating, lighting, scientific research, and solar power generation. The two‐axis tracking employed in the device ensures that the reflected irradiance is aimed at a predetermined target. The design and evaluation of a tilt‐roll two‐axis tracking heliostat are presented in this article. The model consists of a mirror 0.45 m in width and 0.45 m in length installed on a pedestal of height 0.75 m. The motion of the heliostat is controlled using two separate linear drives via a sun‐tracking algorithm implemented in a microcontroller. A small‐scale tilt‐roll design with a reflective area (mirror) of 0.2025 m² is established. This novel design eliminates the need for commercially available solar tracking systems and can be deployed in areas of limited installation space. Dual‐axis heliostat design used here provides an effective way to track the sun's movement for maximum solar energy capture by combining tilt and roll mechanisms. This design ensures tracking precision for optimal solar energy concentration making it well‐suited for experimental and smaller‐scale deployments.

Motivated by a phylogeny reconstruction problem in evolutionary biology, we study the minimum Steiner arborescence problem on directed hypercubes (MSA-DH). Given m, representing the directed hypercube $\vec {Q}_m$, and a set of terminals R, the problem asks to find a Steiner arborescence that spans R with minimum cost. As m implicitly represents $\vec {Q}_{m}$ comprising $2^{m}$ vertices, the running time analyses of traditional Steiner tree algorithms on general graphs does not give a clear understanding of the actual complexity of this problem. We present algorithms that exploit the structure of the hypercube and run in FPT time. We explore the MSA-DH problem on three natural parameters—$|R|$, and two above-guarantee parameters, number of Steiner nodes p and penalty q (defined as the extra cost above m incurred by the solution). For above-guarantee parameters, the parameterized MSA-DH problem take $p \ge 0$ or $q\ge 0$ as input, and outputs a Steiner arborescence with at most $|R|+ p - 1$ or $m+ q$ edges respectively. We present the following results ($\tilde{{\mathcal {O}}}$ hides the polynomial factors): An exact algorithm that runs in $\tilde{{\mathcal {O}}}(3^{|R|})$ time. A randomized algorithm that runs in $\tilde{{\mathcal {O}}}(9^q)$ time with success probability $\ge 4^{-q}$. An exact algorithm that runs in $\tilde{{\mathcal {O}}}(36^q)$ time. A (1+q)-approximation algorithm that runs in $\tilde{{\mathcal {O}}}(1.25284^q)$ time. An ${\mathcal {O}}\left( p\ell _{\textrm{max}}\right)$-additive approximation algorithm that runs in $\tilde{{\mathcal {O}}}(\ell _{\textrm{max}}^{p+2})$ time, where $\ell _{\textrm{max}}$ is the maximum distance of any terminal from the root.

The process of the growth of matter starts with the nucleation of the nanoclusters of functional groups into isolated islands. The growth depends on various deposition parameters and the principle of minimization of surface energies. One of the controlling parameters of the growth is the surface energy; the other parameters are selective nucleation centers, selective growth mechanisms, and controlled organization of nanoclusters of functional groups. The growth can be in the form of discrete islands or dots of different sizes and shapes: wires, tubes, pillars, etc., and thin films.

This chapter gives an introduction to the theme of the book: Nano-Matter Synthesis and Cold Plasma.

Plasma is a quasi-neutral ionized gas. The ionization of individual atoms and molecules typically requires thermal energies of greater than 20000 K. Ionization energy is defined as the energy needed to remove one or more electrons from a neutral atom in the gas phase. The first ionization energy of an element is the energy needed to remove the outermost electron.

In this chapter, an overview of the nano-matter synthesis techniques has been presented. Nanomaterials have been synthesized in different physical, chemical, and mechanical methods that use temperature, pressure, and phase transformation.

To obtain repeatable and reproducible nano-sized clusters, nanotubes, nanorods, and various nanostructures, the fundamental question to be answered is what and how critically the growth parameters are to be controlled. The nano-matter demands a high degree of precision in the growth and process parameters to achieve the desired particle/cluster size. Possible answers to these questions need an understanding of basic nano-thermodynamics and growth kinetics; these topics are dealt with in the next chapter.

This chapter introduces the basic concepts of nucleation of nano-matter and nano-thermodynamics.

The term “plasma” in human physiology refers to the Human blood; it consists of red cells, white cells, and platelets in a liquid; this fluid is relatively clear, yellow-tinted water (92+%), sugar, fat, protein, and salt solution. Normally, 55% of blood’s volume is made up of this liquid. When blood is cleared of its various corpuscles, there remains this transparent liquid, which was named plasma (after the Greek word $\pi \lambda \alpha \sigma \mu \alpha$, which means “moldable substance” or “jelly”). Irving Langmuir first used this term to describe an ionized gas—Langmuir was reminded of the way blood plasma carries red and white corpuscles by the way an electrified fluid carries electrons and ions. Langmuir, along with his colleague Lewi Tonks, was investigating the physics and chemistry of tungsten-filament light bulbs, while achieving a method to extend the lifetime of the filament. In the process, he developed the theory of plasma sheaths—the boundary layers which form between ionized plasmas and solid surfaces. He also discovered that certain regions of a plasma discharge tube exhibit periodic variations of the electron density, which is termed Langmuir waves. This was the genesis of Plasma Physics. Langmuir’s research forms the theoretical basis of most plasma processing techniques for material processing. After Langmuir, plasma research gradually spread in other directions.

TiAl based alloys are currently deployed in extreme service environments, such as jet engine turbine blades. The microstructure of these alloys is a two‐phase lamellar structure, comprising of the majority γ‐TiAl and the minority α 2 ‐Ti 3 Al phases. Understanding the microstructural evolution at high stresses and elevated temperatures is a key requirement to develop the next generation of these alloys. In situ hot stage TEM studies are reported of the mechanisms of lamellar instability and changes in phase fraction of both cold worked and undeformed Ti‐48Al alloys. The effect of cold working on the kinetics of this instability has also been determined. Cross‐sectional TEM samples are prepared on custom designed MEMS chips and in situ heating studies carried out. These results show that neck formation, break‐up of lamellae, and spheroidization are the dominant mechanisms of microstructural instability. An increase in γ‐TiAl phase content is also observed. The strain energy present in the α 2 and γ lamellae in cold worked samples results in microstructural instabilities occurring at lower temperatures in cold worked samples. These findings can be used to design new alloys with improved high temperature stability.

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This paper reframes environmental problems, moving from a crisis of habitability to a problem of ethics, and thus suggests the possibility of creating grounded, subjective politics within the seemingly intractable Anthropocene. To this end, the paper juxtaposes Roy Scranton’s Learning to Die in the Anthropocene with Simone de Beauvoir’s The Ethics of Ambiguity in order to critically examine Scranton’s “philosophical humanism” as a distorted mirror of existentialist “ethical humanism”. Focusing on death and existentialism as central themes, the paper offers a comparison of their conceptions of humanist meaningfulness – conceived as an affect of transcendental capacities in the case of Scranton, and as everyday acts of freedom in de Beauvoir’s philosophy.

A search is reported for charge-parity CP CP violation in ${{{\textrm{D}}}^{{0}}} \rightarrow {{\textrm{K}} _{\text {S}}^{{0}}} {{\textrm{K}} _{\text {S}}^{{0}}}$ D 0 → K S 0 K S 0 decays, using data collected in proton–proton collisions at $\sqrt{s} = 13\,\text {Te}\hspace{-.08em}\text {V}$ s = 13 Te V recorded by the CMS experiment in 2018. The analysis uses a dedicated data set that corresponds to an integrated luminosity of 41.6 $\,\text {fb}^{-1}$ fb - 1 , which consists of about 10 billion events containing a pair of b hadrons, nearly all of which decay to charm hadrons. The flavor of the neutral D meson is determined by the pion charge in the reconstructed decays {{{\textrm{D}}}^{{*+}}} \rightarrow {{{\textrm{D}}}^{{0}}} {{{\mathrm{\uppi }}}^{{+}}} D ∗ + → D 0 π + and {{{\textrm{D}}}^{{*-}}} \rightarrow {\overline{{\textrm{D}}}^{{0}}} {{{\mathrm{\uppi }}}^{{-}}} D ∗ - → D ¯ 0 π - . The CP CP asymmetry in ${{{\textrm{D}}}^{{0}}} \rightarrow {{\textrm{K}} _{\text {S}}^{{0}}} {{\textrm{K}} _{\text {S}}^{{0}}}$ D 0 → K S 0 K S 0 is measured to be $A_{CP} ({{\textrm{K}} _{\text {S}}^{{0}}} {{\textrm{K}} _{\text {S}}^{{0}}} ) = (6.2 \pm 3.0 \pm 0.2 \pm 0.8)\%$ A CP ( K S 0 K S 0 ) = ( 6.2 ± 3.0 ± 0.2 ± 0.8 ) % , where the three uncertainties represent the statistical uncertainty, the systematic uncertainty, and the uncertainty in the measurement of the CP CP asymmetry in the {{{\textrm{D}}}^{{0}}} \rightarrow {{\textrm{K}} _{\text {S}}^{{0}}} {{{\mathrm{\uppi }}}^{{+}}} {{{\mathrm{\uppi }}}^{{-}}} D 0 → K S 0 π + π - decay. This is the first CP CP asymmetry measurement by CMS in the charm sector as well as the first to utilize a fully hadronic final state.

We have synthesized a novel series of nitrogen-doped pentagon-embedded coumarinacenes, namely carbazole-coumarins, via a tandem 1,4-elimination Diels-Alder aromatization reaction. These planar, N-substituted carbazole-coumarins exhibit excellent functionalizability, enhanced photostability and solvent...

This work presents a comparative study on the application of isogeometric analysis in boundary variation methods based topology optimization problems. Level set and phase field are two boundary variation methods gaining in popularity in topology optimization research community. Among different formulations on update methods, this work employs reaction-diffusion and Allen-Cahn update equations for level set and phase field methods respectively. The application of the isogeometric analysis method for these two update equations is new in the literature. The work explores the effect of different parameters, like basis function order, diffusion coefficient, and mesh size on three benchmark topology optimization problems. Our results indicate that quadratic NURBS-basis functions are adequate to solve compliance minimization problems, and increasing order leads to an increase of computation time without much change in accuracy. We found that whereas the phase field method allows a range of diffusion coefficients, the reaction-diffusion-based level set method was able to converge only for a narrow range of diffusion coefficients. Both methods faced convergence problems when the mesh size is increased for higher order basis functions. This study can provide guidance to new users interested in the application of isogeometric analysis in boundary variation methods for topology optimization.

We disclosed an efficient protocol for regioselective C6 C‐H/N‐H activation/annulation reaction of indole‐7‐carboxamides with alkynes to synthesize highly substituted pyrrolo[3,2‐h]isoquinolin‐9‐one derivatives. Under optimized reaction conditions, electron‐deficient and electron‐rich internal alkynes reacted efficiently with various indole‐7‐carboxamides to deliver desired products in good to excellent yields. The synthetic utility of the product is demonstrated by its selective oxidation to the corresponding isatin derivative. Deuterium insertion and intermolecular competition experiments were also conducted to gain mechanistic insights.