Matching Items (1,219)
Filtering by
- All Subjects: psychology
- All Subjects: Mechanical Engineering
Description
Gas Dynamic Virtual Nozzles (GDVN) produce microscopic flow-focused liquid jets and are widely used for sample delivery in serial femtosecond crystallography (SFX) and time-resolved solution scattering. Recently, 2-photon polymerization (2PP) made it possible to produce 3D-printed GDVNs with submicron printing resolution. Comparing with hand- fabricated nozzles, reproducibility, and less developing effort, and similarity of the performance of different 3D printed nozzles are among the advantages of using 3D printing techniques to develop GDVN’s. Submicron printing resolution also makes it possible to easily improve GDVN performance by optimizing the design of nozzles. In this study, 3D printed nozzles were developed to achieve low liquid and gas flow rates and high liquid jet velocities. A double-pulsed nanosecond laser imaging system was used to perform Particle Tracking Velocimetry (PTV) in order to determine jet velocities and assess jet stability/reproducibility. The testing results of pure water jets focused with He sheath gas showed that some designs can easily achieve stable liquid jets with velocities of more than 80 m/s, with pure water flowing at 3 microliters/min, and helium sheath gas flowing at less than 5 mg/min respectively. A numerical simulation pipeline was also used to characterize the performance of different 3D printed GDVNs. The results highlight the potential of making reproducible GDVNs with minimum fabrication effort, that can meet the requirements of present and future SFX and time-resolved solution scattering research.
ContributorsNazari, Reza (Author) / Adrian, Ronald (Thesis advisor) / Kirian, Richard (Thesis advisor) / Herrmann, Marcus (Committee member) / Phelan, Patrick (Committee member) / Weierstall, Uwe (Committee member) / Arizona State University (Publisher)
Created2020
Description
Traditionally, for applications that require heat transfer (e.g. heat exchangers),metals have been the go-to material for manufacturers because of their high thermal as
well as structural properties. However, metals have some notable drawbacks. They are
not corrosion-resistant, offer no freedom of design, have a high cost of production, and
sourcing the material itself. Even though polymers on their own don’t show great
prospects in the field of thermal applications, their composites perform better than their
counterparts. Nanofillers, when added to a polymer matrix not only increase their
structural strength but also their thermal performance. This work aims to tackle two of
those problems by using the additive manufacturing method, stereolithography to solve
the problem of design freedom, and the use of polymer nanocomposite material for
corrosion-resistance and increase their overall thermal performance. In this work, three
different concentrations of polymer composite materials were studied: 0.25 wt%, 0.5
wt%, and 1wt% for their thermal conductivity. The samples were prepared by
magnetically stirring them for a period of 10 to 24 hours depending on their
concentrations and then sonicating in an ice bath further for a period of 2 to 3 hours.
These samples were then tested for their thermal conductivities using a Hot Disk TPS
2500S. Scanning Electron Microscope (SEM) to study the dispersion of the nanoparticles
in the matrix. Different theoretical models were studied and used to compare
experimental data to the predicted values of effective thermal conductivity. An increase
of 7.9 % in thermal conductivity of the composite material was recorded for just 1 wt%
addition of multiwalled carbon nanotubes (MWCNTs).
well as structural properties. However, metals have some notable drawbacks. They are
not corrosion-resistant, offer no freedom of design, have a high cost of production, and
sourcing the material itself. Even though polymers on their own don’t show great
prospects in the field of thermal applications, their composites perform better than their
counterparts. Nanofillers, when added to a polymer matrix not only increase their
structural strength but also their thermal performance. This work aims to tackle two of
those problems by using the additive manufacturing method, stereolithography to solve
the problem of design freedom, and the use of polymer nanocomposite material for
corrosion-resistance and increase their overall thermal performance. In this work, three
different concentrations of polymer composite materials were studied: 0.25 wt%, 0.5
wt%, and 1wt% for their thermal conductivity. The samples were prepared by
magnetically stirring them for a period of 10 to 24 hours depending on their
concentrations and then sonicating in an ice bath further for a period of 2 to 3 hours.
These samples were then tested for their thermal conductivities using a Hot Disk TPS
2500S. Scanning Electron Microscope (SEM) to study the dispersion of the nanoparticles
in the matrix. Different theoretical models were studied and used to compare
experimental data to the predicted values of effective thermal conductivity. An increase
of 7.9 % in thermal conductivity of the composite material was recorded for just 1 wt%
addition of multiwalled carbon nanotubes (MWCNTs).
ContributorsGide, Kunal Manoj (Author) / Nian, Qiong (Thesis advisor) / Kwon, Beomjin (Committee member) / Li, Xiangjia (Committee member) / Arizona State University (Publisher)
Created2020
Description
With the rise of Posttraumatic Stress Disorder (PTSD) among adults in the United States, understanding the processes of trauma, trauma related disorders, and the long-term impact of living with them is an area of continued focus for researchers. This is especially a concern in the case of current and former military service members (veterans), whose work activities and deployment cycles place them at an increased risk of exposure to trauma-inducing experiences but who have a low rate of self-referral to healthcare professionals. There is thus an urgent need for developing procedures for early diagnosis and treatment. The present study examines how the tools and findings of the field of linguistics may contribute to the field of trauma research. Previous research has shown that cognition and language production are closely linked. This study focuses on the role of prosody in PTSD and pilots a procedure for the data collection and analysis. Data consist of monologic talk from a sample of student-veterans and analyzed with speech software (Praat) for pauses greater than 250 milliseconds per 100 words. The pause frequency was compared to a PCL-5 score, an assessment used to check for PTSD symptoms and evaluate need for further assessment and possible diagnosis of PTSD. This pilot study found the methods successfully elicited data that could be used to measure and test the research questions. Although the findings of the study were inconclusive due to limitations of the participant pool, it found that the research model proved effect as a model for future linguistic research on trauma.
ContributorsSouthee, Richard Aaron (Author) / Prior, Matthew T. (Thesis advisor) / Pruitt, Kathryn (Committee member) / Pereira, Jennifer (Committee member) / Arizona State University (Publisher)
Created2020
Description
Transcranial focused ultrasound (tFUS) is a unique neurostimulation modality with potential to develop into a highly sophisticated and effective tool. Unlike any other noninvasive neurostimulation technique, tFUS has a high spatial resolution (on the order of millimeters) and can penetrate across the skull, deep into the brain. Sub-thermal tFUS has been shown to induce changes in EEG and fMRI, as well as perception and mood. This study investigates the possibility of using tFUS to modulate brain networks involved in attention and cognitive control.Three different brain areas linked to saliency, cognitive control, and emotion within the cingulo-opercular network were stimulated with tFUS while subjects performed behavioral paradigms. The first study targeted the dorsal anterior cingulate cortex (dACC), which is associated with performance on cognitive attention tasks, conflict, error, and, emotion. Subjects performed a variant of the Erikson Flanker task in which emotional faces (fear, neutral or scrambled) were displayed in the background as distractors. tFUS significantly reduced the reaction time (RT) delay induced by faces; there were significant differences between tFUS and Sham groups in event related potentials (ERP), event related spectral perturbation (ERSP), conflict and error processing, and heart rate variability (HRV).
The second study used the same behavioral paradigm, but targeted tFUS to the right anterior insula/frontal operculum (aIns/fO). The aIns/fO is implicated in saliency, cognitive control, interoceptive awareness, autonomic function, and emotion. tFUS was found to significantly alter ERP, ERSP, conflict and error processing, and HRV responses.
The third study targeted tFUS to the right inferior frontal gyrus (rIFG), employing the Stop Signal task to study inhibition. tFUS affected ERPs and improved stopping speed. Using network modeling, causal evidence is presented for rIFG influence on subcortical nodes in stopping.
This work provides preliminarily evidence that tFUS can be used to modulate broader network function through a single node, affecting neurophysiological processing, physiologic responses, and behavioral performance. Additionally it can be used as a tool to elucidate network function. These studies suggest tFUS has the potential to affect cognitive function as a clinical tool, and perhaps even enhance wellbeing and expand conscious awareness.
The second study used the same behavioral paradigm, but targeted tFUS to the right anterior insula/frontal operculum (aIns/fO). The aIns/fO is implicated in saliency, cognitive control, interoceptive awareness, autonomic function, and emotion. tFUS was found to significantly alter ERP, ERSP, conflict and error processing, and HRV responses.
The third study targeted tFUS to the right inferior frontal gyrus (rIFG), employing the Stop Signal task to study inhibition. tFUS affected ERPs and improved stopping speed. Using network modeling, causal evidence is presented for rIFG influence on subcortical nodes in stopping.
This work provides preliminarily evidence that tFUS can be used to modulate broader network function through a single node, affecting neurophysiological processing, physiologic responses, and behavioral performance. Additionally it can be used as a tool to elucidate network function. These studies suggest tFUS has the potential to affect cognitive function as a clinical tool, and perhaps even enhance wellbeing and expand conscious awareness.
ContributorsFini, Maria Elizabeth (Author) / Tyler, William J (Thesis advisor) / Greger, Bradley (Committee member) / Santello, Marco (Committee member) / Kleim, Jeffrey (Committee member) / Helms Tillery, Stephen (Committee member) / Arizona State University (Publisher)
Created2020
Description
One potential application of multi-robot systems is collective transport, a task in which multiple mobile robots collaboratively transport a payload that is too large or heavy to be carried by a single robot. Numerous control schemes have been proposed for collective transport in environments where robots can localize themselves (e.g., using GPS) and communicate with one another, have information about the payload's geometric and dynamical properties, and follow predefined robot and/or payload trajectories. However, these approaches cannot be applied in uncertain environments where robots do not have reliable communication and GPS and lack information about the payload. These conditions characterize a variety of applications, including construction, mining, assembly in space and underwater, search-and-rescue, and disaster response.
Toward this end, this thesis presents decentralized control strategies for collective transport by robots that regulate their actions using only their local sensor measurements and minimal prior information. These strategies can be implemented on robots that have limited or absent localization capabilities, do not explicitly exchange information, and are not assigned predefined trajectories. The controllers are developed for collective transport over planar surfaces, but can be extended to three-dimensional environments.
This thesis addresses the above problem for two control objectives. First, decentralized controllers are proposed for velocity control of collective transport, in which the robots must transport a payload at a constant velocity through an unbounded domain that may contain strictly convex obstacles. The robots are provided only with the target transport velocity, and they do not have global localization or prior information about any obstacles in the environment. Second, decentralized controllers are proposed for position control of collective transport, in which the robots must transport a payload to a target position through a bounded or unbounded domain that may contain convex obstacles. The robots are subject to the same constraints as in the velocity control scenario, except that they are assumed to have global localization. Theoretical guarantees for successful execution of the task are derived using techniques from nonlinear control theory, and it is shown through simulations and physical robot experiments that the transport objectives are achieved with the proposed controllers.
Toward this end, this thesis presents decentralized control strategies for collective transport by robots that regulate their actions using only their local sensor measurements and minimal prior information. These strategies can be implemented on robots that have limited or absent localization capabilities, do not explicitly exchange information, and are not assigned predefined trajectories. The controllers are developed for collective transport over planar surfaces, but can be extended to three-dimensional environments.
This thesis addresses the above problem for two control objectives. First, decentralized controllers are proposed for velocity control of collective transport, in which the robots must transport a payload at a constant velocity through an unbounded domain that may contain strictly convex obstacles. The robots are provided only with the target transport velocity, and they do not have global localization or prior information about any obstacles in the environment. Second, decentralized controllers are proposed for position control of collective transport, in which the robots must transport a payload to a target position through a bounded or unbounded domain that may contain convex obstacles. The robots are subject to the same constraints as in the velocity control scenario, except that they are assumed to have global localization. Theoretical guarantees for successful execution of the task are derived using techniques from nonlinear control theory, and it is shown through simulations and physical robot experiments that the transport objectives are achieved with the proposed controllers.
ContributorsFarivarnejad, Hamed (Author) / Berman, Spring (Thesis advisor) / Mignolet, Marc (Committee member) / Tsakalis, Konstantinos (Committee member) / Artemiadis, Panagiotis (Committee member) / Gil, Stephanie (Committee member) / Arizona State University (Publisher)
Created2020
Description
Effective communication plays a major role in the psychological adjustment and quality of the relationship of couples coping with cancer, yet only a few communicative behaviors have been examined in the context of a cancer diagnosis and treatment. This study sought to expand the extant literature by describing a wider range of communicative behaviors (beyond the frequently researched withdraw, disclosure/holding back, and avoidance behaviors) through an observable measure, as previous research has relied heavily on self-report. Couples (134 cancer patients and their caregiving partners) were video-taped discussing a cancer-related concern in the laboratory. Discussions were coded separately for patients and caregivers using the Asymmetrical Behavioral Coding System which captures 22 communicative behaviors. These behaviors contribute to four higher-level scales: positive approach, negative approach, positive avoidance, and negative avoidance. Area under the curve was calculated to describe each factor. The most frequently observed behavior was positive approach, followed by negative avoidance, negative approach, and positive avoidance.
Paired samples t-test analyses examining the factors by moderating variables revealed that women engaged in more positive approach behaviors than did men; men engaged in more avoidant behaviors (both positive and negative) than did women; and caregivers engaged in more avoidant behaviors (both positive and negative) than did patients.
Findings are consistent with prior research in the field and suggest consideration of tailoring possible future interventions. Further investigation is needed to assess possible interactional effects to ultimately help couples better communicate about the challenges associated with cancer treatment and recovery.
Paired samples t-test analyses examining the factors by moderating variables revealed that women engaged in more positive approach behaviors than did men; men engaged in more avoidant behaviors (both positive and negative) than did women; and caregivers engaged in more avoidant behaviors (both positive and negative) than did patients.
Findings are consistent with prior research in the field and suggest consideration of tailoring possible future interventions. Further investigation is needed to assess possible interactional effects to ultimately help couples better communicate about the challenges associated with cancer treatment and recovery.
ContributorsPuleo, Blair Kirsten (Author) / Langer, Shelby (Thesis advisor) / Dillon, Frank (Thesis advisor) / Todd, Michael (Committee member) / Baucom, Brian (Committee member) / Spanierman, Lisa (Committee member) / Arizona State University (Publisher)
Created2020
Description
Prejudice and discrimination toward gender non-conforming individuals is prevalent and extreme in today’s society. This prejudice can manifest in social exclusion, bullying, and victimization, or physical and sexual assault, and can result in negative social, psychological, academic, and physical health outcomes (e.g., depression, anxiety, suicidality). Thus, it is important to understand the perpetrators of gender expression-based aggression and discrimination. In two studies, I addressed how and why people experience prejudice toward gender non-conforming individuals. Using an affordance management theoretical framework, Study 1 identified threats young adults perceived from gender non-conforming peers. There were differences in perceived threats to personal freedoms, social coordination, and values for gender conforming and non-conforming peers, and these perceptions differed by the political ideology of the perceiver. Study 2 explored children’s threat perceptions associated with gender non-conformity. Children perceived threats to social coordination from gender non-conforming peers but not threats to moral values. Results from both studies supported the use of this theoretical framework for studying prejudice toward gender non-conformity. Together, these studies provide unique information about adults’ and children’s reasons for prejudice toward gender non-conforming peers.
ContributorsCook, Rachel (Author) / Martin, Carol L (Thesis advisor) / Neuberg, Steven L. (Committee member) / DeLay, Dawn (Committee member) / Ghavami, Negin (Committee member) / Arizona State University (Publisher)
Created2020
Description
Bicycles and motorcycles offer maneuverability, energy efficiency and acceleration that four wheeled vehicles cannot offer given similar budget for. Two wheeled vehicles have drastically different dynamics from four wheeled vehicles due to their instability and gyroscopic effect from their wheels.
This thesis focuses on self-stabilization of a motorcycle using an active control momentum gyroscope (CMG) and validation of this multi-degree-of-freedom system’s mathematical model. Physical platform was created to mimic the simulation as accurately as possible and all components used were justified. This process involves derivation of a 3 Degree-of-Freedom (DOF) system’s forward kinematics and its Jacobian matrix, simulation analysis of different controller algorithms, setting the system and subsystem specifications, and real system experimentation and data analysis.
A Jacobian matrix was used to calculate accurately decomposed resultant angular velocities which are used to create the dynamics model of the system torque using the Euler-Lagrange method. This produces a nonlinear second order differential equation that is modeled using MATLAB/Simulink. PID, and cascaded feedback loop are tested in this Simulink model. Cascaded feedback loop shows most promises in the simulation analysis. Therefore, system specifications are calculated according to the data produced by this controller method. The model validation is executed using the Vicon motion capture system which captured the roll angle of the motorcycle. This work contributes to creating a set of procedures for creating a validated dynamic model for a CMG stabilized motorcycle which can be used to create variants of other self-stabilizing motorcycle system.
This thesis focuses on self-stabilization of a motorcycle using an active control momentum gyroscope (CMG) and validation of this multi-degree-of-freedom system’s mathematical model. Physical platform was created to mimic the simulation as accurately as possible and all components used were justified. This process involves derivation of a 3 Degree-of-Freedom (DOF) system’s forward kinematics and its Jacobian matrix, simulation analysis of different controller algorithms, setting the system and subsystem specifications, and real system experimentation and data analysis.
A Jacobian matrix was used to calculate accurately decomposed resultant angular velocities which are used to create the dynamics model of the system torque using the Euler-Lagrange method. This produces a nonlinear second order differential equation that is modeled using MATLAB/Simulink. PID, and cascaded feedback loop are tested in this Simulink model. Cascaded feedback loop shows most promises in the simulation analysis. Therefore, system specifications are calculated according to the data produced by this controller method. The model validation is executed using the Vicon motion capture system which captured the roll angle of the motorcycle. This work contributes to creating a set of procedures for creating a validated dynamic model for a CMG stabilized motorcycle which can be used to create variants of other self-stabilizing motorcycle system.
ContributorsMoon, Hansol (Author) / Zhang, Wenlong (Thesis advisor) / Frank, Daniel (Committee member) / Delp, Deana (Committee member) / Sugar, Thomas (Committee member) / Arizona State University (Publisher)
Created2020
Description
Pew Research Center reported in 2015 that already one-in-seven infants born in the United States are Multiracial (Livingston, 2017). Therefore, the number of Multiracial families is growing, and there is a need to understand how parents are engaging in racial-ethnic socialization, or the transmission of messages to Multiracial children about race, ethnicity, and culture (Atkin & Yoo, 2019; Hughes et al., 2006). I conducted a qualitative interview study with 20 Multiracial emerging adults to understand the types of racial-ethnic socialization messages Multiracial youth receive from their parents, and used these themes to inform the development and validation of the first measure of racial-ethnic socialization for Multiracial youth, the Multiracial Youth Socialization (MY-Soc) Scale.
Study 1 identified nine themes of racial-ethnic socialization content: cultural socialization, racial identity socialization, preparation for bias socialization, colorblind socialization, race conscious socialization, cultural diversity appreciation socialization, negative socialization, exposure to diversity socialization, and silent socialization. Study 2 utilized a sample of 902 Multiracial emerging adults to develop and validate the MY-Soc scale. Items were written to assess all of the themes identified in Study 1, with the exception of exposure to diversity socialization, and the survey was designed to collect responses regarding the socialization practices of two of the youths’ primary caregivers. The sample was split to run exploratory factor analysis and confirmatory factor analysis, finding support for a 62-item scale measuring all eight themes. The MY-Soc Scale was also supported by validity and reliability tests. The two studies advance the literature by increasing understanding of the racial-ethnic socialization experiences of Multiracial youth of diverse racial backgrounds. The MY-Soc Scale contributes an important tool for scholars and practitioners to learn which racial-ethnic socialization messages are promotive for Multiracial youth development in different contexts.
Study 1 identified nine themes of racial-ethnic socialization content: cultural socialization, racial identity socialization, preparation for bias socialization, colorblind socialization, race conscious socialization, cultural diversity appreciation socialization, negative socialization, exposure to diversity socialization, and silent socialization. Study 2 utilized a sample of 902 Multiracial emerging adults to develop and validate the MY-Soc scale. Items were written to assess all of the themes identified in Study 1, with the exception of exposure to diversity socialization, and the survey was designed to collect responses regarding the socialization practices of two of the youths’ primary caregivers. The sample was split to run exploratory factor analysis and confirmatory factor analysis, finding support for a 62-item scale measuring all eight themes. The MY-Soc Scale was also supported by validity and reliability tests. The two studies advance the literature by increasing understanding of the racial-ethnic socialization experiences of Multiracial youth of diverse racial backgrounds. The MY-Soc Scale contributes an important tool for scholars and practitioners to learn which racial-ethnic socialization messages are promotive for Multiracial youth development in different contexts.
ContributorsAtkin, Annabelle L. (Author) / Yoo, Hyung Chol (Thesis advisor) / Jackson, Kelly F. (Committee member) / Tran, Alisia G.T.T. (Committee member) / White, Rebecca M.B. (Committee member) / Arizona State University (Publisher)
Created2020
Description
Studies suggest that graduate students experience higher rates of anxiety and depression than their peers outside of academia. Studies also show exercise is correlated with lower levels of anxiety and depression among graduate students. However, despite this evidence, nearly half of graduate students do not exercise regularly. Accordingly, I suggest universities consider adding an exercise requirement to promote graduate student well-being. One potential objection to this recommendation is that an exercise requirement is objectionably paternalistic. I answer this objection with two possible replies. First, there are reasons why the exercise requirement might not be paternalistic, and there may be sufficient non-paternalistic reasons to justify the policy. Second, there are reasons why even if the policy is paternalistic, it is not objectionably paternalistic, and may still be justified. I will offer reasons to consider paternalism in a positive light and why the exercise requirement may be an example of a good paternalistic policy. Because the exercise requirement might be justified on paternalistic grounds, there are reasons to consider other paternalistic policies to promote graduate student well-being.
ContributorsArthur, Philip (Author) / de Marneffe, Peter (Thesis advisor) / Portmore, Doug (Committee member) / DesRoches, Tyler (Committee member) / Arizona State University (Publisher)
Created2020