Investigating the Role of Topological Frustration on Morphology of Novel Multiblock Copolymers

Multiblock copolymers have gained considerable attention due to their ability to offer immense potential for designing soft materials with complex architectures for diverse applications. The enlarged parameter space offered by these multiblock copolymers gives access to a wide variety of multiply continuous morphologies which can be used to produce highly ordered nanostructures. The investigation on multiblock copolymers has been subjected to two critical limitations: (i) A suitable synthetic strategy for accessing these structures and (ii) computational tools which can help in application driven design of these molecules. In this dissertation, the goal was to develop methodologies for the synthesis of multiblock copolymers with different architectures and understand how the variations in molecular architecture can influence macromolecular self-assembly. In chapter 2, the concept of single molecule insertion (SMI) for precise insertion of functional molecules is presented. The molecule precisely inserts once within the polymer chain with high chain fidelity and provides functionalities for post-insertion modifications. A series of molecules satisfying the criteria for SMI based on their reactivity ratios with styrene and methyl methacrylate were examined and used to synthesize a series of multiblock polymers with complex architectures. In chapter 3, a highly efficient synthetic methodology for synthesis of graft copolymers which lie along the continuum of a 3-arm star and A-B-C linear triblock copolymer has been described. The morphological characterization of the synthesized continuum graft copolymers is performed using SAXS, TEM, and DPD simulations. Interesting morphologies are observed for these continuum copolymers and projects them as interesting candidates to access new morphologies. Contrary to most of the work done on block copolymers, these structures are novel as their morphologies can be tuned keeping the φ and χ constant. This study helps in understanding of the effect of polymer architecture on the phase behavior of these graft copolymers and provides a novel pathway to tune the block copolymer morphologies. In chapter 4, a series of PMMA-b-PtBS-b-P2VP and PtBA-b-PtBS-b-P2VP triblock copolymers with extending P2VP arm has been synthesized. The study helps in extending the concept of high χ-low N block copolymer system from diblock to triblock copolymers. The morphologies of the synthesized triblock copolymers were characterized using SAXS and TEM and morphologies with multiple domains and smaller feature size were observed. Also, the effect of extending chain length of P2VP arm on the phase diagram on these highly frustrated triblock copolymer systems was studied and the observed morphologies using SAXS and TEM were mapped with the theoretical predictions

An Online project & portfolio management application: Implementing project selction and prioritization model to reolve priority conflicts and to build strong linkages between projects and the strategic plan

This Capstone Project will address two important problems. The first problem concerns resolving priority conflicts over the projects among the managers in an organization and the second problem concerns the gap between the projects and the organizational strategies. To complete this project, I have developed an online project and portfolio management application by using the software development life cycle methodology and project management methodology. The outcome of this project is a software product that helps in obtaining a general consensus as to which project has the highest priority. This priority awareness helps in resolving conflicts among the managers. This product will force organizations to use the consistent computerized model, the model that helps the organizations to select and prioritize the projects based on their goals and strategic plans

Unsteady flow physics of airfoil dynamic stall

A series of wind tunnel experiments were conducted on an NACA 0012 airfoil undergoing a linear pitch ramp maneuver at a fixed dimensionless pitch rate of 0.05 and across three transitional Reynolds numbers, Re = 200,000, 500,000, and 1,000,000. The primary objectives of these experiments were to perform a detailed analysis of the flow evolution, with particular emphasis on the underlying physical mechanisms, and to extract the dominant scales associated with the flow perturbations, for a canonical dynamic stall process. A series of unsteady surface pressure measurements, with a high sampling frequency, were acquired in order to investigate the time-dependent behavior of the flow in the immediate vicinity of the airfoil. These surface pressure measurements were used to identify the region of boundary layer transition during the initial stages of the dynamic stall process. A spatially-contracting laminar separation bubble was also identified near the airfoil leading edge from the characteristic pressure plateau in the surface pressure distribution. The dominant frequencies associated with the laminar separation bubble were extracted using a continuous wavelet transform technique. These frequencies were observed to span a wide range of chord-based Strouhal numbers between St = 50 and St = 105, at Re = 500,000. The off-body flow evolution was inferred and described using a combination of surface pressure measurements and time-resolved particle image velocimetry. For Re = 200,000 and Re = 500,000, the dynamic stall vortex was observed to emerge from a collective interaction of the discrete vortices that were ejected from the leading edge of the airfoil. At Re = 1,000,000, however, the near-wall vortices were observed to amalgamate into two regions, forming a distinct primary and a secondary coherent structure. After formation, these two structures were observed to interact with each other, following a co-rotating vortex merging process and resulting in the emergence of a single, coherent dynamic stall vortex. The process of emergence of the dynamic stall vortex at Re = 1,000,000, observed from the present experiments, is therefore quite distinct from the classical understanding of the dynamic stall vortex formation, which was observed at the lower Reynolds numbers. The time-dependent spectra of the velocity field were calculated using a combination of empirical mode decomposition and Hilbert transformation. From the velocity spectra, the fluctuations in the flow were observed to attain an amplified state during the initial ejection of vorticity from the leading-edge region of the airfoil. During this amplified phase, the most dominant velocity fluctuations were found to conform to a range of displacement-thickness based Strouhal scales between 0.09 and 0.14. Finally, a numerical implementation of the Orr-Sommerfeld equation was used to extract the spatially-unstable modes associated with the phase-averaged velocity measurements near the airfoil leading edge. The most unstable frequencies from linear stability analysis were found to be consistent with those determined directly from the velocity acquisition during the amplified shedding phase of the dynamic stall process

RESIDUE APPROACH TO MATHEMATICAL ANALYSIS OF THE MOVING COIL GALVANOMETER

In this paper, we present a residue approach fordiscussing the theory of a moving coil galvanometer. This paper presents a new approach to demonstrate the use of the residue approach for obtaining the response of the moving coil galvanometer. The response obtained by this will provide an expression for the deflection of the coil of the moving coil galvanometer from its mean position. In this paper, the responseof the moving coil galvanometer is provided as a demonstration of the application of the residue approach