# Research & Projects

**[Research Project, Jan 2020 - Present] Engineering Photonic Metamaterials**

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**[Research Project, Nov 2019 - Dec 2020] Self-Assembly Pathway Characterization using Manifold Learning**

In molecular self-assembly, the assembly process is driven by the characteristic of building blocks as well as their local environment. The combined result is- self-assembly of a structure takes a distinct pathway in some coordinate system. In a system where a number of different symmetries are observed, identification and characterization of these pathways give crucial information about the behavior of the self-assembly process and the system in general. The task is, however, daunting due to a large number of dimensions involved. At the same time, since the building blocks share similarities, the expectation is that the high dimensional pathway should have some dominant behavior. We use manifold learning techniques to investigate this concept and discover that, the pathway is indeed constrained in the lower-dimensional reduced energy landscape. With a large number of existing libraries and simplicity of the process, this will enable a simple but effective analysis of self-assembly dynamics. For details, please check this presentation.

**[Research Project, July 2019 - Nov 2019] Self-Limiting Finite Size Clusters via Self-Assembly of Defective Colloid Clusters**

In this study, we present a robust method for self-limiting self-assembly of colloidal particles and clusters to synthesize finite size or terminal constructs. In line with the traditional expectation of the self-assembly process, we design the final structure in a bottom-up approach such that once the intended structure is formed, it becomes 'locked' in that configuration. In the proposed approach, we leverage 'defective cluster configurations' that overcomes several crucial shortcomings of available methods. Along with numerical demonstrations, we study the phase transformation and kinetics of several intriguing finite-size configurations generated using this approach. Additionally, the relative simplicity of the building blocks and interaction scheme makes our method experimentally more straightforward. For more info, please see this presentation.

**[Course Project, Fall 2019-20] Controller Design for Inverted Pendulum with Swing Up Control**

Balancing inverted pendulum is a classic problem in control engineering and nonlinear dynamics. In this project, a controller was designed to balance a long inverted pendulum on a cart. The controller was designed using state-space representation with the mathematical model derived from the basic principles of Lagrangian mechanics. An LQR controller, solved using MATLAB was then implemented in LabVIEW to control the instrument. Finally, in addition to balance control, a swing-up subsystem was included in the LabVIEW sketch to automatically swing up the pendulum from downward to upright configuration, after which the LQR took over.

**[Course Project, Spring 2019] Mesh Generation for Irregular Geometries in MATLAB with Application in FEA**

The proper meshing of geometry is undoubtedly one of the major steps toward the solution of structural problems using finite element analysis. However, meshing for irregular geometry is hardly covered in introductory finite element courses/books due to the complexity of the subject matter. An accessible approach to meshing using familiar concepts was presented by (Persson & Strang) called DistMesh where the mesh network is treated as a truss. Inspired by the said work, a MATLAB script was developed to mesh irregular 2D geometries. A meshed geometry was then used in conjunction with FEA script to solve a simple steady-state heat transfer problem. A number of minor improvements have been introduced to the DistMesh program itself.

**[Research Project, Sep 2018 - Apr 2019] Inverse Design for Self-Assembled Superstructure using Colloidal Build Blocks**

One of the promises of nanotechnology is designed materials. The natural choice is bottom-up assembly, that is- building the material from individual components. Self-assembly of colloidal structures with engineered surfaces has been successfully used to construct periodic superstructures of configurable properties. These properties depend on the building blocks used to synthesize the said superstructure. The next stage is, therefore, to establish an algorithmic approach such that for a desired set of properties, the required building block parameters can be calculated. In this project, we establish one such framework using a metaheuristic genetic algorithm. Using this framework, we *inverse design* several colloid metamaterials for optimum photonic bandgap. For details, please see the published work.

**[Research Project, May 2018 - Sep 2018] Analysis of Photonic and Phononic Properties of Self-assembled Colloidal Cluster**

Under suitable conditions, DNA-functionalized colloid particles can self-assemble into designed symmetries. By carefully designing the interaction, it's possible to create artificial material with exotic properties. This study investigates several self-assembly scenarios and investigates the phononic and photonic properties for successfully assembled superstructures.

The project above is an extension of the core ideas of this project and was aimed at automated design and optimization of the assembled system. For details, please of this project, please see the published work by Aryana et. al., 2019.

**[Research Project, 2016 - 17] A New Computational Scheme for Stress Analysis of Boundary-value Problems of Anisotropic Lamina **

This is part of my undergraduate thesis done under the supervision of Prof. Dr. S. Reaz Ahmed at the Department of Mechanical Engineering, Bangladesh University of Engineering and Technology. The aim was to develop a numerically efficient solution method for boundary value problems of anisotropic fiber composites. A summary of the study as follows:

Mathematical modeling of anisotropic fiber composite in terms of a single displacement function.

Formulation of a computational scheme for the mathematical model developed.

Numerical solution of a few chosen problems using MATLAB (Guided cantilever beam, a solid bar under uniaxial tension).

Validation of the method and solution by comparing with contemporary methods (FEM - ANSYS, Analytical Soln).

[Download presentation**]**

**[Research Project, 2016] Displacement Potential Based Numerical Modeling of Elastic Field at Material Interface**

This project focused on a novel numerical methodology to investigate and predict the elastic field in an orthotropic as well as isotropic structure in the presence of heterogeneity. Displacement potential function had been employed for mathematical formulation and FDM had been used to solve few heterogeneous beam problems. This research was done in collaboration with Bibekananda Datta.

**[Mechatronics Project, 2015] Arduino Based Two-Wheeled Balancing Robot**

An Arduino based balancing robot had been constructed and programmed for Junior Year Design project in collaboration with 3 other team members.

The project involved-

Mechanical Design (SolidWorks) & Prototyping

Electrical Circuit Design

Sensor interfacing

Programming (Arduino Programming Language)

PID control algorithm design and tuning.

The poster for this project is available here*.*

**[Mechatronics Project, 2015] Ultrasonic Sensor Based Digital Measurement System**

This Arduino based electronic system employed ultrasonic sensors to (approximately) measure the dimension of a rectangular box placed on the platform in between the sensors. The working principle was simple-

Measure time (t) for each of the sensors to ping (send & receive signal).

Measure dimensions in 2 directions based on signals of 4 sensors.

Height is measured by a 5th sensor at the top.

Calculate dimensions and volume.

This was a team project consisting of 4 members.

**Other ****not-so-notable**** projects: **

**Quadcopter (2014):**The project's aim was to design, build, and program a custom quadcopter using Arduino.Why did it fail? Too complex. Low-cost equipment didn't help either. Also, extremely dangerous without proper setup.

**Solar System Simulation (2015):**A multi-body simulation project in MATLAB. Used to simulate the trajectory of planets under Newtonian mechanics.How accurate it was? No idea. At that time, I had no idea about chaos and numerical stability.

**Pipe Inspection Robot (Assisted, 2014):**An autonomous robot designed to inspect vertical pipes with a diameter of 5 to 5.5 inch.Did it really work? Hardly. The prototype was too heavy and the motors were too weak for sustained vertical climbing even in good pipes.

**Remote Controlled Car (2013):**My first project. An AVR ATmega 32 based wireless controlled car. I hate RF sensors since then.