Scholarly Works, Mechanical Engineering

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  • Using covariant Lyapunov vectors to quantify high-dimensional chaos with a conservation law
    Barbish, John; Paul, Mark R. (American Physical Society, 2023-11-02)
    We explore the high-dimensional chaos of a one-dimensional lattice of diffusively coupled tent maps using the covariant Lyapunov vectors (CLVs). We investigate the connection between the dynamics of the maps in the physical space and the dynamics of the covariant Lyapunov vectors and covariant Lyapunov exponents that describe the direction and growth (or decay) of small perturbations in the tangent space. We explore the tangent space splitting into physical and transient modes and find that the splitting persists for all of the conditions we explore. In general, the leading CLVs are highly localized in space and the CLVs become less localized with increasing Lyapunov index. We consider the dynamics with a conservation law whose strength is controlled by a parameter that can be continuously varied. Our results indicate that a conservation law delocalizes the spatial variation of the CLVs. We find that when a conservation law is present, the leading CLVs are entangled with fewer of their neighboring CLVs than in the absence of a conservation law.
  • The dynamics of an externally driven nanoscale beam that is under high tension and immersed in a viscous fluid
    Barbish, John; Ti, C.; Ekinci, K. L.; Paul, Mark R. (AIP Publishing, 2022-07-15)
    We explore the dynamics of a nanoscale doubly clamped beam that is under high tension, immersed in a viscous fluid, and driven externally by a spatially varying drive force. We develop a theoretical description that is valid for all possible values of tension, includes the motion of the higher modes of the beam, and accounts for a harmonic force that is applied over a limited spatial region of the beam near its ends. We compare our theoretical predictions with experimental measurements for a nanoscale beam that is driven electrothermally and immersed in air and water. The theoretical predictions show good agreement with experiments, and the validity of a simplified string approximation is demonstrated.
  • Pipelines and Power: Psychological Distress, Political Alienation, and the Breakdown of Environmental Justice in Government Agencies’ Public Participation Processes
    Bell, Shannon E.; Hughes, Michael; Tuttle, Grace; Chisholm, Russell; Gerus, Stephen; Mullins, Danielle R.; Baller, Cameron; Scarff, Kelly; Spector, Rachel; Nalamalapu, Denali (Elsevier, 2024-01-25)
    Environmental health research has demonstrated that living near industrial activity is associated with increased stress, depressive symptoms, and feelings of powerlessness. Little is known, however, about the effects of new natural gas pipelines—or the institutional processes dictating their approval and construction—on the mental health of local residents. Through our analysis of a mail survey, an online survey, and a set of semi-structured interviews, we examine how engagement with public participation processes associated with new interstate natural gas pipelines affects mental health. Our results suggest that the public participation opportunities offered by regulatory agencies during the pipeline certification process are primarily performative, and we find that many of the people who have taken part in these performative public input opportunities experience psychological distress, stress-activated physical health effects, and a loss of trust in government institutions. We argue that when people engage in public participation processes that have little or no effect on agency decision-making, it not only disempowers, but can harm those individuals and erode their trust in government institutions. Furthermore, we contend that providing the public with participation opportunities that are merely performative, with little ability to influence decision-making outcomes, is a violation of both procedural and recognition justice, two of the core tenets of environmental justice.
  • PID-Based Longitudinal Control of Platooning Trucks
    Shaju, Aashish; Southward, Steve; Ahmadian, Mehdi (MDPI, 2023-12-05)
    This article focuses on the development and assessment of a PID-based computationally cost-efficient longitudinal control algorithm for platooning trucks. The study employs a linear controller with a nested architecture, wherein the inner loop regulates relative velocities while the outer loop governs inter-vehicle distances within platoon vehicles. The design of the proposed PID controller entails a comprehensive focus on system identification, particularly emphasizing actuation dynamics. The simulation framework used in this study has been established through the integration of TruckSim® and Simulink®, resulting in a co-simulation environment. Simulink® serves as the platform for control action implementation, while TruckSim® simulates the vehicle’s dynamic behavior, thereby closely replicating real world conditions. The significant effort in fine-tuning the PID controller is described in detail, including the system identification of the linearized longitudinal dynamic model of the truck. The implementation is followed by an extensive series of simulation tests, systematically evaluating the controller’s performance, stability, and robustness. The results verify the effectiveness of the proposed controller in various leading truck operational scenarios. Furthermore, the controller’s robustness to large fluctuations in road grade and payload weight, which is commonly experienced in commercial vehicles, is evaluated. The simulation results indicate the controller’s ability to compensate for changes in both road grade and payload. Additionally, an initial assessment of the controller’s efficiency is conducted by comparing the commanded control efforts (total torque on wheels) along with the total fuel consumed. This initial analysis suggests that the controller exhibits minimal aggressive tendencies.
  • Development of an OpenFOAM Solver for Hydroacoustic Simulations: An Application for Acoustic Fish Deterrence
    George, Edwin; Palmore, John A., Jr.; Alexander, William Nathan; Politano, Marcela; Smith, David; Woodley, Christa (2023-11-20)
  • Construction inspection & monitoring with quadruped robots in future human-robot teaming: A preliminary study
    Halder, Srijeet; Afsari, Kereshmeh; Chiou, Erin; Patrick, Rafael; Hamed, Kaveh Akbari (Elsevier, 2023-04-15)
    Construction inspection and monitoring are key activities in construction projects. Automation of inspection tasks can address existing limitations and inefficiencies of the manual process to enable systematic and consistent construction inspection. However, there is a lack of an in-depth understanding of the process of construction inspection and monitoring and the tasks and sequences involved to provide the basis for task delegation in a human-technology partnership. The purpose of this research is to study the conventional process of inspection and monitoring of construction work currently implemented in construction projects and to develop an alternative process using a quadruped robot as an inspector assistant to overcome the limitations of the conventional process. This paper explores the use of quadruped robots for construction inspection and monitoring with an emphasis on a human-robot teaming approach. Technical development and testing of the robotic technology are not in the scope of this study. The results indicate how inspector assistant quadruped robots can enable a human-technology partnership in future construction inspection and monitoring tasks. The research was conducted through on-site experiments and observations of inspectors during construction inspection and monitoring followed by a semi-structured interview to develop a process map of the conventional construction inspection and monitoring process. The study also includes on-site robot training and experiments with the inspectors to develop an alternative process map to depict future construction inspection and monitoring work with the use of an inspector assistant quadruped robot. Both the conventional and alternative process maps were validated through interview surveys with industry experts against four criteria including, completeness, accuracy, generalizability, and comprehensibility. The findings suggest that the developed process maps reflect existing and future construction inspection and monitoring work.
  • Distributed Planning of Collaborative Locomotion: A Physics-Based and Data-Driven Approach
    Fawcett, Randall T.; Ames, Aaron D.; Hamed, Kaveh Akbari (IEEE, 2023-11-14)
    This work aims to provide a computationally effective and distributed trajectory planner at the intersection of physics-based and data-driven techniques for the collaborative locomotion of holonomically constrained quadrupedal robots that can account for and attenuate interaction forces between subsystems. More specifically, this work lays the foundation for using an interconnected single rigid body model in a predictive control framework such that interaction forces can be utilized at the planning layer, wherein these forces are parameterized via a behavioral systems approach. Furthermore, the proposed trajectory planner is distributed such that each agent can locally plan for its own trajectory subject to coupling dynamics, resulting in a much more computationally efficient method for real-time planning. The optimal trajectory obtained by the planner is then provided to a full-order nonlinear whole-body controller for tracking at the low level. The efficacy and robustness of the proposed approach are verified both in simulation and on hardware subject to various disturbances, payloads, and uneven terrains.
  • The study of droplet internal circulation and its interaction with droplet deformation
    Lin, Yushu; Palmore, John A., Jr. (2023-11-19)
    The study of liquid droplet is important for applications like spray-painting, fire suppression, and spray combustion. Droplet morphology has a great impact in these applications, for example, in spray conditions, droplets of various sizes are generated from jet atomization, and the large droplets have strong deformation. The highly deformed droplets have very different characteristics compared to spherical droplets, but many studies on droplet dynamics are based on the spherical droplet assumption. To develop a more accurate modeling of liquid droplet in jet simulations, we use numerical approaches to investigate the mechanism of droplet deformation. Weber number, which measures the balance of surface tension and inertia, is a key non-dimensional group that quantifies droplet deformation. However, droplets with same Weber number do not always have an identical shape. For example, our previous work[Lin and Palmore, 2022] demonstrated that internal circulation also influences droplet shape. Therefore, a deeper understanding in droplet internal circulation is needed. In this work, we will explore a wider range of droplet parameters relevant to a wide array of applications for droplets to study the interaction between droplet internal circulation and deformation.
  • Computation of Direct Sensitivities of Spatial Multibody Systems with Joint Friction
    Verulkar, Adwait; Sandu, Corina; Dopico, Daniel; Sandu, Adrian (ASME, 2022-07)
    Friction exists in most mechanical systems and may have a major influence on the dynamic performance of the system. The incorporation of friction in dynamic systems has been a subject of active research for several years owing to its high nonlinearity and its dependence on several parameters. Consequently, optimization of dynamic systems with friction becomes a challenging task. Gradient-based optimization of dynamical systems is a prominent technique for optimal design and requires the computation of model sensitivities with respect to the design parameters. The novel contribution of this paper is the derivation of the analytical methodology for the computation of direct sensitivities for smooth multibody systems with joint friction using the Lagrangian index-1 formulation. System dynamics have been computed using two different friction models; the Brown and McPhee, and the Gonthier et al. model. The methodology proposed to obtain model sensitivities has also been validated using the complex finite difference method. A case study has been conducted on a spatial multibody system to observe the effect of friction on the dynamics and model sensitivities, compare sensitivities with respect to different parameters and demonstrate the numerical and validation aspects. Since design parameters can have very different magnitudes and units, the sensitivities have been scaled with the parameters for comparison. Finally, a discussion has been presented on the interpretation of the case study results. Due to the incorporation of joint friction, ‘jumps’ or discontinuities are observed in the model sensitivities akin to those observed for hybrid dynamical systems.
  • Generating synthetic as-built additive manufacturing surface topography using progressive growing generative adversarial networks
    Seo, Junhyeon; Rao, Prahalada; Raeymaekers, Bart (2023-12-04)
    Numerically generating synthetic surface topography that closely resembles the features and characteristics of experimental surface topography measurements reduces the need to perform these intricate and costly measurements. However, existing algorithms to numerically generated surface topography are not well-suited to create the specific characteristics and geometric features of as-built surfaces that result from laser powder bed fusion (LPBF), such as partially melted metal particles, porosity, laser scan lines, and balling. Thus, we present a method to generate synthetic as-built LPBF surface topography maps using a progressively growing generative adversarial network. We qualitatively and quantitatively demonstrate good agreement between synthetic and experimental as-built LPBF surface topography maps using areal and deterministic surface topography parameters, radially averaged power spectral density, and material ratio curves. The ability to accurately generate synthetic as-built LPBF surface topography maps reduces the experimental burden of performing a large number of surface topography measurements. Furthermore, it facilitates combining experimental measurements with synthetic surface topography maps to create large data-sets that facilitate, e.g. relating as-built surface topography to LPBF process parameters, or implementing digital surface twins to monitor complex end-use LPBF parts, amongst other applications.
  • Layered control for cooperative locomotion of two quadrupedal robots: Centralized and distributed approaches
    Kim, Jeeseop; Fawcett, Randall T.; Kamidi, Vinay R.; Ames, Aaron D.; Akbari Hamed, Kaveh (Institute of Electrical and Electronics Engineers, 2023)
    This paper presents a layered control approach for real-time trajectory planning and control of robust cooperative locomotion by two holonomically constrained quadrupedal robots. A novel interconnected network of reduced-order models, based on the single rigid body (SRB) dynamics, is developed for trajectory planning purposes. At the higher level of the control architecture, two different model predictive control (MPC) algorithms are proposed to address the optimal control problem of the interconnected SRB dynamics: centralized and distributed MPCs. The distributed MPC assumes two local quadratic programs that share their optimal solutions according to a one-step communication delay and an agreement protocol. At the lower level of the control scheme, distributed nonlinear controllers are developed to impose the full-order dynamics to track the prescribed reduced-order trajectories generated by MPCs. The effectiveness of the control approach is verified with extensive numerical simulations and experiments for the robust and cooperative locomotion of two holonomically constrained A1 robots with different payloads on variable terrains and in the presence of disturbances. It is shown that the distributed MPC has a performance similar to that of the centralized MPC, while the computation time is reduced significantly.
  • Engineered live bacteria as disease detection and diagnosis tools
    Tanniche, Imen; Behkam, Bahareh (2023-10-24)
    Sensitive and minimally invasive medical diagnostics are essential to the early detection of diseases, monitoring their progression and response to treatment. Engineered bacteria as live sensors are being developed as a new class of biosensors for sensitive, robust, noninvasive, and in situ detection of disease onset at low cost. Akin to microrobotic systems, a combination of simple genetic rules, basic logic gates, and complex synthetic bioengineering principles are used to program bacterial vectors as living machines for detecting biomarkers of diseases, some of which cannot be detected with other sensing technologies. Bacterial whole-cell biosensors (BWCBs) can have wide-ranging functions from detection only, to detection and recording, to closed-loop detection-regulated treatment. In this review article, we first summarize the unique benefits of bacteria as living sensors. We then describe the different bacteria-based diagnosis approaches and provide examples of diagnosing various diseases and disorders. We also discuss the use of bacteria as imaging vectors for disease detection and image-guided surgery. We conclude by highlighting current challenges and opportunities for further exploration toward clinical translation of these bacteria-based systems.
  • Interfacial Dynamics in Dual Channels: Inspired by Cuttlebone
    Huang, Matthew; Frohlich, Karl; Esmaili, Ehsan; Yang, Ting; Li, Ling; Jung, Sunghwan (MDPI, 2023-10-01)
    The cuttlebone, a chambered gas-filled structure found in cuttlefish, serves a crucial role in buoyancy control for the animal. This study investigates the motion of liquid-gas interfaces within cuttlebone-inspired artificial channels. The cuttlebone’s unique microstructure, characterized by chambers divided by vertical pillars, exhibits interesting fluid dynamics at small scales while pumping water in and out. Various channels were fabricated with distinct geometries, mimicking cuttlebone features, and subjected to different pressure drops. The behavior of the liquid-gas interface was explored, revealing that channels with pronounced waviness facilitated more non-uniform air-water interfaces. Here, Lyapunov exponents were employed to characterize interface separation, and they indicated more differential motions with increased pressure drops. Channels with greater waviness and amplitude exhibited higher Lyapunov exponents, while straighter channels exhibited slower separation. This is potentially aligned with cuttlefish’s natural adaptation to efficient water transport near the membrane, where more straight channels are observed in real cuttlebone.
  • Experimental and theoretical model for the origin of coiling of cellular protrusions around fibers
    Sadhu, Raj Kumar; Hernandez-Padilla, Christian; Eisenbach, Samo Penič; Zhang, Lixia; Vishwasrao, Harshad D.; Behkam, Bahareh; Konstantopoulos, Konstantinos; Shroff, Hari; Iglič, Aleš; Peles, Elior; Nain, Amrinder S.; Gov, Nir S. (Nature Research, 2023-09-12)
    Protrusions at the leading-edge of a cell play an important role in sensing the extracellular cues during cellular spreading and motility. Recent studies provided indications that these protrusions wrap (coil) around the extracellular fibers. However, the physics of this coiling process, and the mechanisms that drive it, are not well understood. We present a combined theoretical and experimental study of the coiling of cellular protrusions on fibers of different geometry. Our theoretical model describes membrane protrusions that are produced by curved membrane proteins that recruit the protrusive forces of actin polymerization, and identifies the role of bending and adhesion energies in orienting the leading-edges of the protrusions along the azimuthal (coiling) direction. Our model predicts that the cell’s leading-edge coils on fibers with circular cross-section (above some critical radius), but the coiling ceases for flattened fibers of highly elliptical cross-section. These predictions are verified by 3D visualization and quantitation of coiling on suspended fibers using Dual- View light-sheet microscopy (diSPIM). Overall, we provide a theoretical framework, supported by experiments, which explains the physical origin of the coiling phenomenon.
  • Unified Learning from Demonstrations, Corrections, and Preferences during Physical Human-Robot Interaction
    Mehta, Shaunak A.; Losey, Dylan P. (ACM, 2023)
    Humans can leverage physical interaction to teach robot arms. This physical interaction takes multiple forms depending on the task, the user, and what the robot has learned so far. State-of-the-art approaches focus on learning from a single modality, or combine multiple interaction types by assuming that the robot has prior information about the human?s intended task. By contrast, in this paper we introduce an algorithmic formalism that unites learning from demonstrations, corrections, and preferences. Our approach makes no assumptions about the tasks the human wants to teach the robot; instead, we learn a reward model from scratch by comparing the human?s inputs to nearby alternatives. We first derive a loss function that trains an ensemble of reward models to match the human?s demonstrations, corrections, and preferences. The type and order of feedback is up to the human teacher: we enable the robot to collect this feedback passively or actively. We then apply constrained optimization to convert our learned reward into a desired robot trajectory. Through simulations and a user study we demonstrate that our proposed approach more accurately learns manipulation tasks from physical human interaction than existing baselines, particularly when the robot is faced with new or unexpected objectives.
  • High-Frequency Dielectrophoresis Reveals That Distinct Bio-Electric Signatures of Colorectal Cancer Cells Depend on Ploidy and Nuclear Volume
    Duncan, Josie L.; Bloomfield, Mathew; Swami, Nathan; Cimini, Daniela; Davalos, Rafael V. (MDPI, 2023-09-01)
    Aneuploidy, or an incorrect chromosome number, is ubiquitous among cancers. Whole-genome duplication, resulting in tetraploidy, often occurs during the evolution of aneuploid tumors. Cancers that evolve through a tetraploid intermediate tend to be highly aneuploid and are associated with poor patient prognosis. The identification and enrichment of tetraploid cells from mixed populations is necessary to understand the role these cells play in cancer progression. Dielectrophoresis (DEP), a label-free electrokinetic technique, can distinguish cells based on their intracellular properties when stimulated above 10 MHz, but DEP has not been shown to distinguish tetraploid and/or aneuploid cancer cells from mixed tumor cell populations. Here, we used high-frequency DEP to distinguish cell subpopulations that differ in ploidy and nuclear size under flow conditions. We used impedance analysis to quantify the level of voltage decay at high frequencies and its impact on the DEP force acting on the cell. High-frequency DEP distinguished diploid cells from tetraploid clones due to their size and intracellular composition at frequencies above 40 MHz. Our findings demonstrate that high-frequency DEP can be a useful tool for identifying and distinguishing subpopulations with nuclear differences to determine their roles in disease progression.
  • Scale modeling of thermo-structural fire tests
    Gangi, Michael J.; Lattimer, Brian Y.; Case, Scott W. (Wiley, 2023-03)
    Standard methods for fire resistance testing require large-scale assemblies and are typically conducted on specialized furnaces at considerable cost. This research focused on developing a scaling methodology for a reduced-scale fire resistance test that reduces the size of the test article while maintaining the same thermal and structural response exhibited in the large-scale test. The developed scaling methodology incorporates uniform geometric scaling, Fourier number time scaling, and furnace boundary condition matching. The scaling laws were experimentally validated with fire exposure tests on gypsum wallboard samples at three scales (full-scale, 1/2-scale, and 1/6-scale). In the tests, samples were exposed to a full-scale equivalent of 60-min of ASTM E119 fire curve exposure on a reduced-scale horizontal furnace, and the temperature rise through the thickness profile was measured. Models were created to calculate the modified fire curves for the smaller-scale tests. Experimental results show that on the exposed surface, the 1/2-scale absolute temperature was within 1.7% of full-scale, while the 1/6-scale temperature was within 2.5%. While the time-dependent properties of burning and cracking caused visual differences in these gypsum tests, modeling and temperature measurements demonstrated that the test results were thermally similar. The good similarity of temperatures is achievable in fire exposure tests of non-combustible gypsum wallboard down to 1/6-scale.
  • Phononic Bandgap Programming in Kirigami By Unique Mechanical Input Sequencing
    Khosravi, Hesameddin; Li, Suyi (Wiley, 2023-04)
    This study investigates the programming of elastic wave propagation bandgaps in periodic and multi-stable metamaterials by intentionally and uniquely sequencing its constitutive mechanical bits. To this end, stretched kirigami is used as a simple and versatile testing platform. Each mechanical bit in the stretched kirigami can switch between two stable equilibria with different external shapes (aka. "(0)" and "(1)" states). Therefore, by designing the sequence of (0) and (1) bits, one can fundamentally change the underlying periodicity and thus program the phononic bandgap frequencies. This study develops an algorithm to identify the unique periodicities generated by assembling "n-bit strings" consisting of n mechanical bits. Based on a simplified geometry of these n-bit strings, this study also formulates a theory to uncover the rich mapping between input sequencing and output bandgaps. The theoretical prediction and experiment results confirm that the (0) and (1) bit sequencing is effective for programming the phonic bandgap frequencies. Moreover, one can additionally fine-tune the bandgaps by adjusting the global stretch. Overall, the results of this study elucidate new strategies for programming the dynamic responses of architected material systems.
  • Design, development, and analysis of the lower body of next-generation 3D-printed humanoid research platform: PANDORA
    Fuge, Alexander J.; Herron, Connor W.; Beiter, Benjamin C.; Kalita, Bhaben; Leonessa, Alexander (Cambridge University Press, 2023-04)
    The main contribution of this paper is the design and development of the lower body of PANDORA (3D-Printed Autonomous humaNoid Developed for Open-source Research Applications), a new humanoid robotic platform implementing additive manufacturing techniques. The three joint configurations (hip, knee, and ankle) along with the major three structural parts (pelvis, thigh, and shin) of the lower body are discussed. The use of 3D printing and PLA+ material makes the robot an affordable solution for humanoid robotics research that gives a high power-to-weight ratio by significantly reducing the number of parts, as well as manufacturing and assembly time. The range of motion of the lower body of PANDORA has been investigated and is found to be comparable to a human lower body. Further, finite element analysis has been performed on the major parts of the lower body of PANDORA to check the structural integrity and to avoid catastrophic failures in the robot. The use of in-house developed actuators and robot electronics reduces the overall cost of the robot and makes PANDORA easily accessible to the research communities working in the field of humanoids. Overall, PANDORA has the potential for becoming popular between researchers and designers for investigating applications in the field of humanoid robotics, healthcare, and manufacturing, just to mention a few. The mechanical designs presented in this work are available open source to lower the knowledge barrier in developing and conducting research on bipedal robots.
  • Actin Filaments Couple the Protrusive Tips to the Nucleus through the I-BAR Domain Protein IRSp53 during the Migration of Cells on 1D Fibers
    Mukherjee, Apratim; Ron, Jonathan Emanuel; Hu, Hooi Ting; Nishimura, Tamako; Hanawa-Suetsugu, Kyoko; Behkam, Bahareh; Mimori-Kiyosue, Yuko; Gov, Nir Shachna; Suetsugu, Shiro; Nain, Amrinder Singh (Wiley-VCH, 2023-03)
    The cell migration cycle, well-established in 2D, proceeds with forming new protrusive structures at the cell membrane and subsequent redistribution of contractile machinery. Three-dimensional (3D) environments are complex and composed of 1D fibers, and 1D fibers are shown to recapitulate essential features of 3D migration. However, the establishment of protrusive activity at the cell membrane and contractility in 1D fibrous environments remains partially understood. Here the role of membrane curvature regulator IRSp53 is examined as a coupler between actin filaments and plasma membrane during cell migration on single, suspended 1D fibers. IRSp53 depletion reduced cell-length spanning actin stress fibers that originate from the cell periphery, protrusive activity, and contractility, leading to uncoupling of the nucleus from cellular movements. A theoretical model capable of predicting the observed transition of IRSp53-depleted cells from rapid stick-slip migration to smooth and slower migration due to reduced actin polymerization at the cell edges is developed, which is verified by direct measurements of retrograde actin flow using speckle microscopy. Overall, it is found that IRSp53 mediates actin recruitment at the cellular tips leading to the establishment of cell-length spanning fibers, thus demonstrating a unique role of IRSp53 in controlling cell migration in 3D.