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Computational modeling of the effects of process parameters on the grain morphology of additively manufactured stainless steel
Get PDFThe microstructure of the parts created using Directed Energy Deposition (DED) additive manufacturing method, vary notably due to a change in the processing parameters. Since there is a direct relation between grain morphology and the mechanical properties of a part, understanding the effects of each process parameter on the grain morphology is critical towards optimal fabrication of parts using DED method. In this study, Kinetic Monte Carlo (KMC) method was used to model the DED of parts made of 304L stainless steel. In order to simulate the grain evolution, KMC Potts model, which is a statistical mechanics model, was implemented. Using this model, the fusion zone that comprises the melt pool and Heat Affected Zone (HAZ) are simulated as two concentric ellipsoids. The kinetics provided by the fusion zone results in grain growth. To see each process parameter’s effect on the grain morphology, a parametric study was conducted on the effect of scanning speed and layer thickness on the microstructure of deposited material. The final results were analyzed qualitatively and quantitatively by using an image processing software. It was found that by increasing the scanning speed, the number of fine grains at the centerline of the laser path increases significantly. In addition, we found that in very small layer thicknesses, fine grains cannot grow and mostly disappear. This happens as a result of a too small layer thickness compared to the depth of the melt pool, which results in each layer being melted multiple times due to passage of laser on the subsequent layers
Investigating various parts of the nervous system to model motion
Get PDFThe motion control system involves a complex network of structures that are observed at all levels of the central nervous system. Different parts of the brain, especially the cerebral cortex, the cerebellum, and basal ganglia, have an important role in the motion system. Motion commands are transmitted through the motor neurons in the spinal cord to the muscles and motion organs. At the level of the spinal cord, some control operations are performed on the motion system, such as reflexes and adjustment of motor neuron coefficients. The harmonious and complex movements that require skill are performed through the circuits that exist between the cortex, the basal ganglia, and the cerebellum. In this study, we examine the factors affecting movement and describe the role of each item in a specialized way
An argument for sensuous revolution and its manifestation in the food system
Get PDFIn this food system, we witness issues such as health disparities, social injustice, and environmental injustice, which all flow within one another. When seeking to address such issues it is essential to recognize their inherent interconnectedness and root causes; otherwise, intended solutions can perpetuate the issues they aim to solve when they do not encompass full-seeing. The greatest barrier to full-seeing is disconnection with experience, which occurs when what we are experiencing is obscured by static conceptions. This inhibition of holistic understanding, when occurring through such limited perspectives, makes solving issues such as health disparities, social injustice, and environmental injustice an unintelligible pursuit. The intention of this paper is to identify the static, limited conceptions we have around ourselves and food, which can be dismantled and reformed through engagement in a sensuous revolution where we realize ourselves as embedded within a holistic circle of sustenance
The impact of water infrastructure inequality on marginalized communities
Get PDFAmerica’s current system of water infrastructure poses a threat not only to the environment but also to public health. The water crisis reveals the stark inequalities that exist from both an environmental justice and a social justice perspective. There is a growing concern that without adequate investment from federal resources, the problems related to this issue will only worsen the longer they are neglected. There is little information about how specific environmental and social factors combine with water infrastructure to create long-term infrastructure inequalities. However, this thesis explores the disparities in water infrastructure affordability, vulnerability patterns, and environmental hazards. It also examines the relationship between these variables and the adaptive capacity of disadvantaged communities. As these communities experience this infrastructural inequality on a much larger scale, we are driven to explore the root cause of these problems. Understanding the overlap between the social issues and environmental ones is key in developing strategies to strengthen the environmental and economic resilience of unempowered communities. In the United States, an estimated 1.1 million individuals lack a piped water connection, 73% of which are located close to a networked supply. Isolated statistics like these give only a glimpse into a problem that has much more severe consequences. Drawing on statistical analysis and research, this paper explores sociodemographic patterns of racial, economic, and geographic disparities that characterize water inequity. In the Southeast region especially, these findings show connections between historically discriminative legislation and current infrastructure issues. While there has been research on water justice, there has not been significant evidence to suggest connections between race, income, and geographic location relative to the amount of exposure from environmental causes. This thesis argues that water infrastructure inequality in America should be framed as an issue of social and environmental justice that looks at the structural inequalities of race and class regarding the growing climate crisis. Implementing systems that provide adequate water infrastructure in the United States is a growing issue that continues to threaten the health and safety of public welfare every day
Optimal electric vehicle charging management: coordination of multiple charging methods and technologies
Get PDFThe global electric vehicle (EV) industry continues to expand rapidly. From the power grid perspective, expanding EV adoption could adversely impact the grid if its load is left uncontrolled. EV users also deal with challenges such as high charging time and low charger availability, especially in urban areas with huge populations and various types of charging demands. This dissertation initially reviews EV charging technologies and presents a new classification. Next, to address the EV charging management challenges, it investigates optimal EV charging management models and studies the coordination of different charging methods and technologies. This work has two major parts: (i) EVs\u27 Operation and Control Algorithm and (ii) EVs\u27 Optimization Considering Multiple Charging Technologies. In the first part of this dissertation, a distributed optimization framework is developed based on the alternating direction method of multipliers (ADMM) as an exchange problem to solve the electric vehicle charging management problem (EVCMP). Next, the proposed framework is expanded by employing a collaboration layer between different EV aggregators (EVA) to increase the optimization\u27s overall efficiency while preserving EVAs\u27 independence. The proposed coordinated distributed platform (CDP) enhances the load profile\u27s smoothness compared to the locally coordinated and uncoordinated charging platforms and decreases EV charging costs. In the second part, we introduced a multi-charger framework including both fixed and mobile charging stations for optimal operation of EVs, which covers the shortcomings of stand-alone usage of each charging technology. The proposed framework selects the best charging station type and location to minimize the users\u27 overall charging time and cost and mitigate the stress on the electricity network caused by EV charging, especially during peak hours
Modeling of laminar-to-turbulent transition using a hybrid multi-scale simulation strategy
Get PDFLaminar-to-turbulent transition is a phenomenon observed in practical applications. Robust computational models are needed to predict the onset of transition and the associated flow dynamics. Direct numerical simulation (DNS), although suitable for fundamental studies, tends to be computationally expensive, thus making large-eddy simulations (LES) a viable strategy. In LES, large scales of the flow field are computed, and the effects of small scales are modeled. In this study, the hybrid two-level large-eddy simulation strategy (TLS-LES) is being assessed for its ability to predict features of transition. The TLS-LES strategy blends the two-level simulation (TLS) and LES models. TLS is a multi-scale model, in which both large and small scales are computed. The present work compares the TLS-LES approach with the other models by simulating temporal transition within two canonical flows: the Taylor-Green Vortex and plane Poiseuille flow. The assessment is performed by comparing the results against corresponding DNS
Helping Psych Students Understand Their Employable Skill Set
Get PDFIntroduction Psychology students are underemployed after graduation despite being a part of one of the largest majors nationwide (Burning Glass Technologies, 2018; The Ladders, 2019; National Center for Education Statistics, 2019). In order to remedy this, our study will investigate how many and which careers psychology students are minimally qualified for. We hypothesize the knowledge skills and abilities (KSAOs) psychology students obtain during their undergraduate career will ensure they are minimally qualified for a wide range of careers across industries after graduation. Methods and Analyses In the previous stage of our research project (Todd et al., 2021), we compiled and validated a list of 42 KSAOs psychology students gained from their undergraduate curriculum by interviewing subject matter experts (i.e., faculty) via Qualtrics on the level of each KSAO obtained by a C student in a psychology class using a 1-7 Likert scale. In this stage, we will use those KSAO level scores in conjunction with O*Net data on the KSAOs necessary to perform a job to identify roles psychology students are minimally qualified for meaning they meet most, 80%, of the job requirements. Our analyses will involve compiling the KSAOs a student has from the courses they’ve taken and ranking their level of each KSAO on the highest level obtained (e.g. two courses with the same KSAO but different levels of expertise). That list of KSAOs will then be compared against O*Nets database of KSAO requirements for careers. Individuals will be returned a list of careers in which 80% of the required KSAOs for those careers match with those they obtained through their coursework. Expected Results and Implications We expect to confirm our hypothesis that the KSAOs psychology students obtain during their undergraduate career will make them minimally eligible for a range of careers across industries. The implications of this finding reside in its use with the website we plan to launch, Eugene. This program will allow psychology students to insert a list of classes and return the KSAOs they have and to which level and the careers correlated with those KSAOs. This will help students grasp a broader understanding of their competencies as well as careers they are eligible for
Optimization for a Sturm--Liouville problem with the spectral parameter in the boundary condition
Get PDFWe find an optimal mass of a structure described by a Sturm-Liouville (S-L) problem with a spectral parameter in the boundary conditions. While previous work on the subject focused on a somewhat simplified model, we consider a more general S-L problem. We use the calculus of variations approach to determine a set of critical points of a corresponding mass functional, yet these critical points - which we call \textit{predesigns} - do not necessarily themselves represent meaningful solutions. It is natural to expect a mass to be real and positive. To this end, we additionally introduce a set of solvability conditions on the S-L problem data, confirming that these critical points represent meaningful solutions we refer to as \textit{designs}. We further present the analytic continuation of these predesigns in regards to the spectral parameter as well as a discussion of the stability of these (pre)designs. We present a code that allows us to for the given data of the S-L problem check conditions of solvability, plot the design, and calculate the value of the functional that represents the optimal mass
Belongingness needs, personality, and the influence of virtual socialization
Get PDFSocial belongingness is a part of everyday life. The purpose of this study was to learn more about how personality and the use of virtual socialization interact with feelings of belongingness and subjective well-being. The findings of this study indicate that belongingness and well-being are significantly and positively correlated with extraversion. We also found that belongingness and social media used for maintaining friendships were significantly correlated. Further, in a regression analysis, extraversion consistently and significantly positively predicted perceived belongingness. These findings suggest that personality and modality of socializing interact with perceived belongingness
Modeling of Spiral Waves Arising in Atrial Fibrillation
Get PDFThe objective of this study is to model spirals arising in atrial fibrillation. Spiral wave fronts, known to cardiologists as cardiac rotors, are responsible for heart arrhythmias. The modeling of the path of the spiral will ultimately assist in understanding why arrhythmias occur and how to treat them. This study involved first developing a linear ray model to provide basic understanding of a rotating wave front, then generalizing to spiral models. Both the Archimedean spiral and a spiral derived from the diffusion equation are used as possible candidates to resemble cardiac rotors found in the heart. We conclude by comparing the two spirals strike frequencies to electrodes and discuss their non-Doppler anomalies