Department of Mechanical Engineering

Large language models (LLMs) such as ChatGPT and Google Bard have garnered significant attention in the academic community. Previous research has evaluated these LLMs for various applications such as generating programming exercises and solutions. However, these evaluations have predominantly been conducted by instructors and researchers, not considering the actual usage of LLMs by students. This study adopts a student-first approach to comprehensively understand how undergraduate computer science students utilize ChatGPT, a popular LLM, released by OpenAI. We employ a combination of student surveys and interviews to obtain valuable insights into the benefits, challenges, and suggested improvements related to ChatGPT. Our findings suggest that a majority of students (over 57%) have a convincingly positive outlook towards adopting ChatGPT as an aid in coursework-related tasks. However, our research also highlights various challenges that must be resolved for long-term acceptance of ChatGPT amongst students. The findings from this investigation have broader implications and may be applicable to other LLMs and their role in computing education.

This research paper aims to analyze the strengths and weaknesses associated with the utilization of ChatGPT as an educational tool in the context of undergraduate computer science education. ChatGPT's usage in tasks such as solving assignments and exams has the potential to undermine students' learning outcomes and compromise academic integrity. This study adopts a quantitative approach to demonstrate the notable unreliability of ChatGPT in providing accurate answers to a wide range of questions within the field of undergraduate computer science. While the majority of existing research has concentrated on assessing the performance of Large Language Models in handling programming assignments, our study adopts a more comprehensive approach. Specifically, we evaluate various types of questions such as true/false, multi-choice, multi-select, short answer, long answer, design-based, and coding-related questions. Our evaluation highlights the potential consequences of students excessively relying on ChatGPT for the completion of assignments and exams, including self-sabotage. We conclude with a discussion on how can students and instructors constructively use ChatGPT and related tools to enhance the quality of instruction and the overall student experience.

Dielectric elastomers (DEs) have significant potential in many applications, particularly in the realm of soft robotics, owing to their capability of undergoing large deformation. The viscoelastic creep response exhibited by dielectric elastomers when subjected to electrostatic input is an inherent characteristic of DEs that hinders their long-term performance and applicability. This behavior leads to time-dependent deformation during actuation, which limits their use as actuators in applications such as robotic grasping. This work presents control techniques that have been developed to minimize viscoelastic creep in dielectric elastomer actuators (DEAs). To simulate the viscoelastic creep behavior of DEAs under dynamic loading, a dynamic modeling framework is presented. The equations derived from the dynamic model are subsequently subjected to the two different control strategies using Linear Quadratic Regulator and Model Predictive Control. Control strategies have been devised to minimize creep and decrease the reaction time. The key aspect of both methods involve the development of an objective function, which is then optimized to determine the ideal control input voltage. The suggested control methods involve applying the fundamental optimal control concepts to an actuator. The actuator response on the application of a single-step input is observed. This principle is then extended to include the actuator response which is a multi-step signal using the proposed control strategy. The results suggest that the control methods are capable of efficiently dealing with the viscoelastic properties of the actuator to achieve different desired equilibrium conditions and hence optimize the performance of the actuator. The simulation results demonstrate that both the control strategies reduce the response time of the DEA by about 98% and also improve the steady-state response. This paper’s findings have the potential to be applied to the development of a control system for the mitigation of viscoelastic creep in DEAs.

Voxelization is a standard technique to represent arbitrary shaped geometries on a Cartesian grid. It is often utilized in pre-processing stage of any computational fluid dynamics (CFD) simulation for distinguishing the fluid and solid domain. In addition, identification of boundary fluid nodes in the immediate vicinity of the solid body is extremely crucial for proper imposition of boundary conditions and force evaluation. These nodes are therefore tagged separately and is often termed as surface voxelization. However, this procedure becomes non-Trivial and computationally expensive as the complexity of geometry increases, especially if it is deformable and moving. Here voxelization needs to be performed in the solid volume as well, as the nodes keep switching from solid to fluid and vice versa at every iteration. For fluid-structure interaction problems, the analysis of flow behaviour requires an additional operation where the point of intersection of the lattice links connecting the fluid boundary nodes and solid bound nodes need to be further calculated. This ensures that deformation of geometry is properly captured and the correct boundary velocity is enforced onto the fluid (no slip). In this work we present techniques for GPU acceleration of voxelization for moving deformable geometries intended for CFD solvers based on the lattice Boltzmann method (LBM). The proposed techniques show speed-ups of up to 5.1x over equivalent parallel implementations.

Many applications of multi-robot systems require them to achieve a segregated formation in a finite amount of time and then perform subsequent tasks without colliding with each other. This paper proposes a finite-time Model Predictive Control (MPC) based framework for such systems. This includes a cost function to ensure finite-time convergence to segregated formation and a constraint for collision avoidance. An upper bound on the time steps required by the robots to converge to the segregated formation is also derived. Moreover, such systems often suffer from perturbations in the states of the robots, which may produce jitters in their motion profiles. A bound-based Aperiodic Motion Smoothing method is also integrated to ensure a smooth motion profile for the robots, even in the presence of perturbations in their states. By appropriate selection of bound on perturbations, the communication between the sensor and controller can be minimized by reducing the number of triggers. The performance of the proposed framework is verified via simulations and hardware implementation by performing the segregation of five robots.

Unplanned urbanization and industrialization have become threats to the sustainability of services in the cities of India. This article explores the relationship between land use spatial pattern, vegetation cover, water, and varying configurations of industrial land use in Kota City, Rajasthan, India, from the year 1990 to 2020. The study utilizes remote sensed Landsat data for analyzing the spatial-temporal dynamics of the landscape. A supervised classification approach is adopted to classify three decadal data. Spatial metrics are utilized to quantify the spatial configuration of the landscape. It was observed that a significant urban expansion has occurred in the city mainly in the northwestern direction on fertile lands, with a severe loss of traditional water bodies within the city. Lately, the rocky southern landscape of Kota city has been used for performing agriculture.

The droplet motion, deformation and breakup is widely investigated as it is prevalent in many applications such as IC engines, gas turbines, rocket engines, medical devices and airborne disease transmission. A comprehensive body of experimental and numerical studies exists for droplet subjected to continuous gas streams. However, in certain situations like thermoacoustic instabilities in rocket engines and gas turbines, the droplet is subjected to a pulsatile flow, and droplet behavior under these conditions is investigated in this work. Numerical simulations are performed using the finite volume technique, applying the Volume of Fluid (VOF) method to track the droplet-gas interface effectively. The adaptive mesh refinement technique effectively reduces cell count and, hence, the computational cost. The 3-D simulations for steady flow are validated with the experimental data. Next, the pulsatile flow is simulated using a time-dependent sinusoidal gas velocity and the effects of amplitude and frequency on breakup time and droplet evolution are studied. The 3-D pulsatile simulation compares well with the 2-D pulsatile simulation, which is computationally much less expensive and hence used extensively for parametric studies. The breakup time is compared with that of uniform flow conditions. The pulsation of the crossflow stream was found to accelerate the breakup process. The pulsation amplitude is found to affect more than the frequency of flow.

The objectives of this present work is to study the stability and bifurcation control of an idealized electrostatically actuated microcantilever MEMS device that can widely observe in the field MEMS application. Here, the cantilever based device has been modelled as a spring-mass-damper system considering both the linear and nonlinear spring and damper. Simultaneously, the cantilever based device is excited harmonically by applied voltages. The method of multiple scales is employed to obtain the reduced order equations in terms of amplitude and phase those are directly used to determine the approximate the solutions for different resonance conditions. The catastrophic failure of the system may occur due to the presence of saddle-node and pitchfork bifurcation points as it leads the jump phenomenon. Basins of attractions are plotted in order to find the initial condition for a specific solution in a region having more than one solution. The obtained results can successfully be used in designing the microcantilever based devices that depict typical realistic nonlinear characteristics in the field of MEMS application. © 2012 The Authors. Published by Elsevier Ltd.