IU Indianapolis ScholarWorks :: Browsing by Subject "modeling"

Browsing by Subject "modeling"

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Automatic Modeling and Simulation of Networked Components
(2011) Bruce, Nathaniel William; Koskie, Sarah; Chen, Yaobin; Li, Lingxi
Testing and verification are essential to safe and consistent products. Simulation is a widely accepted method used for verification and testing of distributed components. Generally, one of the major hurdles in using simulation is the development of detailed and accurate models. Since there are time constraints on projects, fast and effective methods of simulation model creation emerge as essential for testing. This thesis proposes to solve these issues by presenting a method to automatically generate a simulation model and run a random walk simulation using that model. The method is automated so that a modeler spends as little time as possible creating a simulation model and the errors normally associated with manual modeling are eliminated. The simulation is automated to allow a human to focus attention on the device that should be tested. The communications transactions between two nodes on a network are recorded as a trace file. This trace file is used to automatically generate a finite state machine model. The model can be adjusted by a designer to add missing information and then simulated in real-time using a software-in-the-loop approach. The innovations in this thesis include adaptation of a synthesis method for use in simulation, introduction of a random simulation method, and introduction of a practical evaluation method for two finite state machines. Test results indicate that nodes can be adequately replaced by models generated automatically by these methods. In addition, model construction time is reduced when comparing to the from scratch model creation method.
Design of Self-Supported 3D Printed Parts for Fused Deposition Modeling
(ASME, 2016-08) Lischke, Fabian; Tovar, Andres; Department of Mechanical Engineering, School of Engineering and Technology
One of the primary challenges faced in Additive Manufacturing (AM) is reducing the overall cost and printing time. A critical factor in cost and time reduction is post-processing of 3D printed (3DP) parts, of which removing support structures is one of the most time consuming steps. Support is needed to prevent the collapse of the part or certain areas under its own weight during the 3D printing process. Currently, the design of self-supported 3DP parts follows a set of empirical guide lines. A trial and error process is needed to produce high quality parts by Fused Depositing Modeling (FDM). The usage of chamfer angle with a max 45° angle form the horizontal for FDM is a common example. Inclined surfaces with a smaller angle are prone to defects, however no theoretical basis has been fully defined, therefore a numerical model is needed. The model can predict the problematic areas at a print, reducing the experimental prints and providing a higher number of usable parts. Physical-based models have not been established due to the generally unknown properties of the material during the AM process. With simulations it is possible to simulate the part at different temperatures with a variety of other parameters that have influence on the behavior of the model. In this research, analytic calculations and physical tests are carried out to determine the material properties of the thermoplastic polymer Acrylonitrile - Butadiene - Styrene (ABS) f or FDM at the time of extrusion. This means that the ABS is going to be extruded at 200°C to 245°C and is a viscous material during part construction. Using the results from the physical and analytical models, i.e., Timoshenko’s modified beam theory for micro-structures, a numerical material model is established to simulate the filament deformation once it is deposited onto the part. Experiments were also used to find the threshold for different geometric specifications, which could then be applied to the numerical model to improve the accuracy of the simulation. The result of the finite element analysis is compared to experiments to show the correlation between the prediction of deflection in simulation and the actual deflection measured in physical experiments. A case study was conducted using an application that optimizes topology of complex geometries. After modeling and simulating the optimized part, areas of defect and errors were determined in the simulation, then verified and and measured with actual 3D prints.
Design, Modeling, and Fabrication of a Ventilator Prototype - A Successful Student Project Story
(ASME, 2021-11) Yeong, Haoyee; Iloeje, Francis; Kindomba, Eli; Folorunso, Sunday; Li, Yafeng; Zhang, Jing; Mechanical and Energy Engineering, School of Engineering and Technology
Abstract In this work, we use a group project approach for a group of undergraduate students to design and develop a mechanical ventilator, in response to the COVID-19 pandemic. A student group project composed of a team of undergraduate students has successfully designed and fabricated a mechanical bag valve mask (BVM) ventilator prototype. It is lightweight with a single controller is driven, capable of volume adjustment, inexpensive, open-source, and designed for ease of fabrication, installation, and operation by the average user. The ventilator prototype also consists of 3D printed components and stored bought hardware. A finite element model was developed to analyze the deformation of the bag valve mask. Finally, the ventilator system is fully tested functioning properly.
Finite Element Modeling of Coating Thickness Using Heat Transfer Method
(Elsevier, 2021-01) Li, Yafeng; Dhulipalla, Anvesh; Zhang, Jian; Park, Hye-Yeong; Jung, Yeon-Gil; Koo, Dan Daehyun; Zhang, Jing; Mechanical and Energy Engineering, School of Engineering and Technology
A new heat transfer based finite element model is proposed to simulate coating thickness in the electron-beam physical vapor deposition (EB-PVD) process. The major advantage of the proposed model is that it is much computationally efficient than the traditional ray-tracing based model by about two orders of magnitude. This is because the Gaussian distribution heating source has the same profile as the cosine relation used in the ray-tracing method. Firstly, the model simulates the temperature profile of a metal substrate heated by a heating source with a Gaussian distribution. Then using a calibrated conversion process, the temperature profile is converted to corresponding coating thickness. The model is successfully demonstrated by three validation cases, including a stationary disk, a stationary cylinder, and a rotary three-pin component. The predicted coating thicknesses in the validation cases are in good agreement with either the ray-tracing based analytical solution or experimental data. After its validation, the model is applied to a rotary turbine blade to predict its coating thickness distribution. In summary, the model is capable to simulate coating thickness in complex shaped parts.
Meth math: modeling temperature responses to methamphetamine
(American Physiological Society (APS), 2014-04-15) Molkov, Yaroslav I.; Zaretskaia, Maria V.; Zaretsky, Dmitry V.; Department of Emergency Medicine, IU School of Medicine
Methamphetamine (Meth) can evoke extreme hyperthermia, which correlates with neurotoxicity and death in laboratory animals and humans. The objective of this study was to uncover the mechanisms of a complex dose dependence of temperature responses to Meth by mathematical modeling of the neuronal circuitry. On the basis of previous studies, we composed an artificial neural network with the core comprising three sequentially connected nodes: excitatory, medullary, and sympathetic preganglionic neuronal (SPN). Meth directly stimulated the excitatory node, an inhibitory drive targeted the medullary node, and, in high doses, an additional excitatory drive affected the SPN node. All model parameters (weights of connections, sensitivities, and time constants) were subject to fitting experimental time series of temperature responses to 1, 3, 5, and 10 mg/kg Meth. Modeling suggested that the temperature response to the lowest dose of Meth, which caused an immediate and short hyperthermia, involves neuronal excitation at a supramedullary level. The delay in response after the intermediate doses of Meth is a result of neuronal inhibition at the medullary level. Finally, the rapid and robust increase in body temperature induced by the highest dose of Meth involves activation of high-dose excitatory drive. The impairment in the inhibitory mechanism can provoke a life-threatening temperature rise and makes it a plausible cause of fatal hyperthermia in Meth users. We expect that studying putative neuronal sites of Meth action and the neuromediators involved in a detailed model of this system may lead to more effective strategies for prevention and treatment of hyperthermia induced by amphetamine-like stimulants.
Microcomputed Tomography Applications in Bone and Mineral Research
(2013-09) Bart, Zachary R.; Wallace, Joseph M.
Microcomputed tomography (μCT) has evolved as a development of simple X-ray imaging into an indispensable technique used in both laboratory research and clinical diagnostics. Commercially available systems are capable of creating images at sub-micrometer resolutions to map out the complex web of trabecular bone in small animals, and offer an accurate measurement of bone mineral density for patients at risk of osteoporotic fractures. This review describes the development of μCT, its ability to analyze bone, and how it can be used alongside other clinical and laboratory techniques. μCT offers a non-destructive alternative for imaging mineralized tissues with no required preparation and can also be utilized with living specimen to track skeletal development.
Modeling and Design of an Electrical Mower Deck Control System
(2020-05) Fu, Li; Li, Lingxi; Chien, Stanley; Chen, Yaobin
With the development of the electric mower, an electrical control system is necessary to drive the blades and the traction wheel. This thesis introduces an electrical deck control system. The system includes a high-powered deck controller and a permanent magnet synchronous motor (PMSM). A PMSM control model has been built in MATLAB/Simulink to verify and support the physical design. Three different PWM modulation methods have also been implemented and compared in MATLAB/Simulink. Furthermore, a model for the distribution and features of grass was built based on sampling of Google Street View images. A six-step pulse width modulation (PWM) control strategy was realized using a PIC33 embedded microprocessor. An enhanced closed-loop control system design was implemented to keep a constant blade speed in order to cut grass efficiently.
Numerical Simulation of Impact Behavior of Ceramic Coatings Using Smoothed Particle Hydrodynamics Method
(ASME, 2021-04) Zhang, Jian; Lu, Zhe; Sagar, Sugrim; Choi, Hyunhee; Jung, Yeon-Gil; Park, Heesung; Koo, Dan Daehyun; Zhang, Jing; Mechanical and Energy Engineering, School of Engineering and Technology
In this work, the impact behavior of an alumina spherical particle on alumina coating is modeled using the smoothed particle hydrodynamics (SPH) method. The effects of impact angle (0 deg, 30 deg, and 60 deg) and velocity (100 m/s, 200 m/s, and 300 m/s) on the morphology changes of the impact pit and impacting particle, and their associated stress and energy are investigated. The results show that the combination of impact angle of 0 deg and velocity of 300 m/s produces the highest penetration depth and largest stress and deformation in the coating layer, while the combination of 100 m/s and 60 deg causes the minimum damage to the coating layer. This is because the penetration depth is determined by the vertical velocity component difference between the impacting particle and the coating layer, but irrelevant to the horizontal component. The total energy of the coating layer increases with the time, while the internal energy increases with the time after some peak values, which is due to energy transmission from the spherical particle to the coating layer and the stress shock waves. The energy transmission from impacting particle to coating layer increases with the increasing particle velocity and decreases with the increasing inclined angle. The simulated impact pit morphology is qualitatively similar to the experimental observation. This work demonstrates that the SPH method is useful to analyze the impact behavior of ceramic coatings.
Retinal Ganglion Cells With a Glaucoma OPTN(E50K) Mutation Exhibit Neurodegenerative Phenotypes when Derived from Three-Dimensional Retinal Organoids
(Elsevier, 2020-07-14) VanderWall, Kirstin B.; Huang, Kang-Chieh; Pan, Yanling; Lavekar, Sailee S.; Fligor, Clarisse M.; Allsop, Anna R.; Lentsch, Kelly A.; Dang, Pengtao; Zhang, Chi; Tseng, Henry C.; Cummins, Theodore R.; Meyer, Jason S.; Medical and Molecular Genetics, School of Medicine
Retinal ganglion cells (RGCs) serve as the connection between the eye and the brain, with this connection disrupted in glaucoma. Numerous cellular mechanisms have been associated with glaucomatous neurodegeneration, and useful cellular models of glaucoma allow for the precise analysis of degenerative phenotypes. Human pluripotent stem cells (hPSCs) serve as powerful tools for studying human disease, particularly cellular mechanisms underlying neurodegeneration. Thus, efforts focused upon hPSCs with an E50K mutation in the Optineurin (OPTN) gene, a leading cause of inherited forms of glaucoma. CRISPR/Cas9 gene editing introduced the OPTN(E50K) mutation into existing lines of hPSCs, as well as generating isogenic controls from patient-derived lines. RGCs differentiated from OPTN(E50K) hPSCs exhibited numerous neurodegenerative deficits, including neurite retraction, autophagy dysfunction, apoptosis, and increased excitability. These results demonstrate the utility of OPTN(E50K) RGCs as an in vitro model of neurodegeneration, with the opportunity to develop novel therapeutic approaches for glaucoma.
Stochastic Termination of Spiral Wave Dynamics in Cardiac Tissue
(Frontiers, 2022-01-25) Rappel, Wouter-Jan; Krummen, David E.; Baykaner, Tina; Zaman, Junaid; Donsky, Alan; Swarup, Vijay; Miller, John M.; Narayan, Sanjiv M.; Medicine, School of Medicine
Rotating spiral waves are self-organized features in spatially extended excitable media and may play an important role in cardiac arrhythmias including atrial fibrillation (AF). In homogeneous media, spiral wave dynamics are perpetuated through spiral wave breakup, leading to the continuous birth and death of spiral waves, but have a finite probability of termination. In non-homogeneous media, however, heterogeneities can act as anchoring sources that result in sustained spiral wave activity. It is thus unclear how and if AF may terminate following the removal of putative spiral wave sources in patients. Here, we address this question using computer simulations in which a stable spiral wave is trapped by an heterogeneity and is surrounded by spiral wave breakup. We show that, following ablation of spatial heterogeneity to render that region of the medium unexcitable, termination of spiral wave dynamics is stochastic and Poisson-distributed. Furthermore, we show that the dynamics can be accurately described by a master equation using birth and death rates. To validate these predictions in vivo, we mapped spiral wave activity in patients with AF and targeted the locations of spiral wave sources using radiofrequency ablation. Targeted ablation was indeed able to terminate AF, but only after a variable delay of up to several minutes. Furthermore, and consistent with numerical simulations, termination was not accompanied by gradual temporal or spatial organization. Our results suggest that spiral wave sources and tissue heterogeneities play a critical role in the maintenance of AF and that the removal of sources results in spiral wave dynamics with a finite termination time, which could have important clinical implications.

Browsing by Subject "modeling"

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