Engineering

Permanent URI for this collectionhttps://hdl.handle.net/10323/11890

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Investigating Effect of Organization Structure and Cognitive Profiles on Engineering Team Performance Using Agent Based Models and Graph Theory
(2025-01-01) Estes, Judson Bert; Pandey, Vijitashwa; Mourelatos, Zissimos P.; Drignei, Dorin; Malik, Ali A.
Engineering organizations have to maximize return on investment (ROI) on the products they design and market. Involvement of human decision makers complicates the design process because not only their technical skills affect the results, but also their other cognitive skills in addition to their role and seniority in the organization. These cannot be studies easily within existing organizations for logistical reasons, while at the same time human-subject research is time consuming and difficult. An agent-based model, building upon previous research, is employed in this work which addresses both the above issues. The contributions of this work include an agent-based framework for modeling and simulating engineering design as informed by the organization structure which is represented by a network graph. In particular, the model uses a scale-free network using the Barabasi-Albert algorithm. Using the undirected graph thus generated, we use the eigenvector centrality to depict the realtive influence of a team-member on design decisions. This comprehensive model allowed us to investigate a wide variety of problem settings and the effect of cognitive profiles on the engineering design process. Individuals' intrinsic and organization-induced cognitive skills were incorporated into the model. The model also allowed for the individuals' cognitive profiles to affect and be affected by their experience in the team design effort. Based on our results, we were able to show that organizations that promote collaborative work, particularly with the aim of engaging skilled individuals, are more likely to come up with better designs and/or converge to designs faster
Harvesting Energy and Water from Fertilizer Osmosis
(2022-01-01) Pourmovahed, Pouyan; Maisonneuve, Jonathan; Guessous, Laila; Hansen, Fay; Lefsrud, Mark; Wang, Xia
The potential for concentrated fertilizer to drive water treatment, nutrient recovery, and power generation has received increased attention. Large amounts of energy are wasted in agricultural systems each time concentrated fertilizers are diluted in water for fertigation, such as is common in hydroponic cultivation. This energy can be harnessed and converted to mechanical work or electricity to take a considerable load off specific farm subsystems, such as pumping and ventilation, or can directly drive desalination and filtration of non-potable waters such as seawater and wastewater. This thesis analyzes membrane processes for converting fertilizer energy to useful work. First, the novel concept of using fertilizer to generate power via pressure retarded osmosis (PRO) is introduced. Second, the concept of fertilizer PRO is experimentally validated, and power generation and energy recovery are shown for a range of common fertilizers. Third, the thermodynamic and practical limitations of recovering energy from fertilizer are established using a number of new analytical, numerical, and experimental methods. Finally, an alternative to energy recovery is examined, namely the possibility of using fertilizer to drive forward osmosis (FO) to recover clean irrigation water from wastewater feed sources. The limitations of fertilizer FO are also established, again using a number of new analytical, numerical, and experimental methods. Results indicate that up to 1200 l of water and 125 Wh of energy may theoretically be recovered per kg of fertilizer, when low-concentration municipal wastewater is available. Given typical nutrient requirements for hydroponic plant cultivation, such values approach nearly 500 of necessary irrigation water and 5 of the electricity consumed by a typical greenhouse. However, practical limitations and non-ideal transport dynamics reduce these values and must be overcome in future research, so that fertilizer energy can be economically deployed to farm systems. To conclude, other applications of fertilizer energy are introduced and pathways for future research and development are discussed. This research may contribute to the future of sustainable agriculture by opening up new possibilities for energy efficiency, water security, and food productivity.
Development of Predictive and Nonlinear Control Designs for an Electric All Wheel Drive Powertrain System
(2024-01-01) Ross, Anthony; Das, Manohar; Cheok, Ka C; Kobus, Christopher; Tomlin, Kasaundra
Vehicle electrification is a strong trend in the automotive industry. The use of electric motors for propulsion offers many opportunities and some technical difficulties. This thesis addresses the challenge of controlling and coordinating two electric motors as part of an electric all wheel drive (eAWD) powertrain to maintain vehicle stability during longitudinal and lateral motion of the vehicle. The control problem is broken into two pieces, vehicle level control and control of the electric motors. At the vehicle level, several control strategies are developed and compared. First, a weighted one step ahead (WOSA) controller is developed. Next, a nonlinear model predictive controller (NLMPC) is developed. Next, a feedback linearization controller (FLC) is developed. Finally, a sliding mode controller (SMC) is developed. In each case, the vehicle level controller is integrated with fuzzy rules to translate the vehicle level control signal into reference targets for the motor controllers. The integration of a physical model and fuzzy rules into a single controller is a unique concept that is explored in this thesis. Each of the electric motors consists of a traction motor and torque vectoring motor. WOSA controllers are developed for each type of motor and integrated with the vehicle level controller for overall vehicle control. The WOSA is a simple but powerful control approach for the motor controllers. Key system states are estimated using the controller output observer (COO) concept. The COO provides a good estimate of the system states with sensor data that is already available on typical vehicles. The COO also uses the WOSA control strategy. For both longitudinal and lateral motion, the effectiveness of the control strategies are demonstrated for launch and a high speed double lane change maneuver on high friction and low friction road surfaces using Simulink and CarSim
Development of Speckle Interferometry for Simultaneous Dual Sensitive Measurement
(2023-01-01) Zheng, Xiaowan; Yang, Lianxiang; Barber, Gary; Arefifar, S. Ali; Yang, Ankun; Yang, Cunxiang
Digital speckle interferometry involves two main methods: digital speckle pattern interferometry (DSPI/Digital Holography) and digital speckle pattern shear interferometry (Digital Shearography). This technology allows for non-destructive, full-field, high-precision measurements. In early stages, speckle interferometry was limited to measuring a single parameter in a single test, like in-plane or out-of-plane deformation or the first derivative of displacement (strain) along horizontal or vertical directions. However, advancements in speckle technology now allow simultaneous measurement of two of above parameters. These measurements systems, though, have limitations - they possess a single spatial resolution, resulting in certain drawbacks during deformation detection and non-destructive testing, such as difficulty in evaluating dense fringes or overlooking smaller defects. Recent advancements have led to a new study using digital shearography, measuring one parameter with two different spatial resolutions. However, due to its recent emergence, there's limited literature on this method. Both measuring two parameters with one spatial resolution and measuring one parameter with two spatial resolutions are referred to as dual-sensitive measurement. This study mainly concentrates on simultaneous measurement of target parameters using speckle pattern interferometry technology. It delves into two key areas: enhancing digital shearography to achieve dual parameters and dual spatial resolution measurements, and developing novel digital holography for dual spatial resolutions. The novel digital holography method employs different-sized fields of view and polarization techniques to establish independent optical channels. Unlike shearography systems, it uses spatial carrier phase-shifting technology to separate overlapped intensity maps. This method proves more convenient and practical than traditional methods by eliminating the need to adjust shear directions. Ultimately, this technique can simultaneously produce dual-sensitive measurement results at different spatial resolutions, reducing the need for redundant measurements and saving time and labor costs. With ongoing enhancements, this technology holds significant promise for industrial applications and interest researchers focused on experimental mechanics via speckle/holographic interferometry
Crowding Reduction and Waiting Time Analysis in Health-Care System Using Machine Learning
(2022-01-01) Hijry, Hassan Mohmmed; Olawoyin, Richard; McDonald, Gary; Edward, William; Debnath, Debatosh
In the hospital setting, the emergency room (ER) offers timely emergency care for patients and is considered the busiest department because of the urgency of cases. Emergency rooms have the highest number of patients overcrowding within any hospital; more than 50 of the patients admitted to the hospital come through the ER. Healthcare management is continuously trying to minimize wait times and optimize the hospitals allocated resources, but most ERs still suffer from the overcrowding crisis due to the stochastic arrival and random arrival distribution. Advanced techniques, such as machine learning algorithms, are useful for determining real life queue scenarios and patient flow (e.g., waiting time in queue and length of stay), which are considered measures of ER overcrowding. As such, we began by building a model to predict patient length of stay through predictive input factors such as patient age, mode of arrival, and patient’s type of condition using three machine learning algorithms (e.g., artificial neural networks (ANN), linear regression, and logistic regression). The best model accuracy ANN resulted in an increase of 19.5 compared to the performance from previous studies. Then, the Deep Learning Model was applied for historical queueing variables to vi predict patient waiting time in a system alongside, or in place of, queueing theory (QT). Four optimization algorithms (SGD, Adam, RMSprop, and AdaGrade) were applied and compared to find the best model with the lowest mean absolute error. The results showed that the SGD algorithm achieved better prediction accuracy than the traditional approach and reduced the use of assumptions. Moreover, the model decreased the error reduction by 24 when compared to prior literature. Lastly, we proposed a model to predict the patient waiting time based on the lab test results. Multi-algorithms were implemented by using real-life COVID-19 test results data recorded during the pandemic. Among the eight proposed models, the results showed that decision tree regression performed better for predicting waiting times. Based on experiments performed in the research, this dissertation provides a guideline for waiting time analysis in the queue—not only in healthcare, but also in other sectors, considering model understandability and the feature extraction process.
Efficacy Of Telerehabilitation In Improving Grip Strength
(2022-11-13) James, Sam Prasanna Rajkumar; Sengupta, Sankar; Conrad, Megan; Dean, Brian; McDonald, Gary
Handgrip strength is essential to perform day-to-day tasks. People lose handgrip strength due to aging, diseases, and other conditions. According to neuroplasticity principles, grip strength can be improved using repetitive tasks and exercises. People often are not motivated enough to adhere to meaningless repeated movements to improve grip strength exercises. This study describes developing an innovative smartphone-based telerehabilitation system that includes an innovatively designed grip strength device (eGripper) and a phone application to play games. This telerehabilitation system encourages patients to play a game while improving grip strength.eGripper was a repurposed dynamometer that sends grip strength data to an android phone. The raw grip strength data stream was used as a control variable to play games. In this study, the grippyBird game was designed, where customizations can be done from a remote therapist dashboard. Thirty-four participants participated in validity and reliability experiments to measure this device against the “gold” standard Jamar dynamometer. The test results substantiate that eGripper has acceptable concurrent validity and inter-instrumental reliability. A randomized clinical trial with an experimental and control group measured efficacy and compliance. Findings from the clinical trial showed significant improvements in grip strength and compliance between groups. A formative and summative usability testing was performed. Formative usability used focus groups and informal interviews with a few therapists and patients during the design stage. Four experimental participants did a summative usability experiment with two surveys. An eGripper telerehabilitation system to resolve the issues of HEP compliance was developed for this study. The use of a game instead of repetitive exercises motivated participants to be compliant in performing their HEP more regularly. Future research is needed to continue developing both the eGripper and associated games to help patients with poor hand strength improve their ability to grip.
Stochastic Planning And Scheduling For Reconfigurable Job Shops And Flow Lines
(2022-11-11) Imseitif, Jad Taysir; Nezamoddini, Nasim; Aydas, Osman; Pandey, Vijitashwa; Cheok, Ka C
The uncertain and competitive market is leading manufacturers to look for fast and effective technological solutions to manage their production systems and make them highly responsive to market needs. Moreover, customers are requesting customized, high-quality products quickly and at low costs. Utilizing rigid manufacturing systems such as dedicated manufacturing systems (DMSs) or flexible manufacturing systems (FMSs) limits manufacturers’ responsiveness. Reconfigurable manufacturing systems (RMSs) were introduced to cope with these challenges. These systems are built around modularity and reconfigurability and use reconfigurable machine tools (RMTs) as their main component. The adjustable structure of RMT allows the system to adapt to market requirements. However, production management in RMSs is a particularly challenging task compared to traditional systems, which makes manufacturers skeptical about adopting these systems. To address this issue, this dissertation presents novel methodologies to manage production activities within RMSs regarding planning, scheduling, and control. The research was conducted in two main parts based on the system type (i.e., job shop or flow line). A novel mixed-integer linear programming (MILP) model for planning and scheduling is formulated for the former. Then, it was extended to a two-stage stochastic (TSS) formulation to incorporate the uncertainties in volume and machines’ productivity. A data-driven controller with predictive capabilities was developed for the latter. It collects real-time data to reschedule raw material injection time and control the inner-stage movement of work-in-process (WIP) units to optimize their levels. The applicability of the proposed models was validated using case studies adopted from the literature. The result of this dissertation showed the cost-benefits of utilizing RMSs and the effectiveness of adopting the proposed methodologies to manage RMSs.

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