View All Items
(81 - 100 of 203)
Pages
- Title
- THE ROLE OF CONTENT MODALITY ON THE LIKABILITY OF AN ONLINE COMMUNICATOR.
- Creator
-
Pharmer, Rebecca L, Whitten, Shannon, University of Central Florida
- Abstract / Description
-
With the growing popularity of social media platforms like Facebook, human interaction in online environments is increasing. As a result, social perceptions of the individuals "behind the screen" has become a topic that needs to be explored. The present study explores how the media platform (specifically Facebook post versus Video) affects perceptions of an individual with a controversial opinion. Potentially, the same content in a video format may increase the likability of the presenter in...
Show moreWith the growing popularity of social media platforms like Facebook, human interaction in online environments is increasing. As a result, social perceptions of the individuals "behind the screen" has become a topic that needs to be explored. The present study explores how the media platform (specifically Facebook post versus Video) affects perceptions of an individual with a controversial opinion. Potentially, the same content in a video format may increase the likability of the presenter in contrast to reading the same opinions in Facebook posts. The present study examined the role of alignment of opinion (agree vs. disagree with presenter) and content modality (Facebook video vs. Facebook text post) on participants' perception of likeability towards the online persona. In this study, three hypotheses were tested. The first hypothesis is that video posts will generally yield more likability for the presenter about a controversial issue than the same content in a Facebook post. Second, people who agree with the presenter's position of a controversial issue will find the person posting more likable. Finally, an interaction is expected such that likability will be most affected for the participants who disagree with the presenter; specifically those participants who disagree will be more likely to like the presenter in the video condition, whereas format will matter less for those who agree with the presenter's opinion. The dependent variables of the present study are the Interpersonal Adjective Scale (IAS, Trapnell & Wiggins 1990) and scores on the Basic Empathy Scale in Adults (BES-A, Jolliffe and Farrington, 2006).
Show less - Date Issued
- 2018
- Identifier
- CFH2000434, ucf:45717
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH2000434
- Title
- ROLE OF ADRENERGIC NEURONS IN MOTOR CONTROL: EXAMINATION OF CEREBELLAR PURKINJE NEURONS IN MICE FOLLOWING SELECTIVE ADRENERGIC CELL ABLATION IN VIVO.
- Creator
-
Mansour, Monica, Ebert, Steven, University of Central Florida
- Abstract / Description
-
Phenylethanolamine-N-methyltransferase (Pnmt) is the enzyme that catalyzes the conversion of noradrenaline to adrenaline. These catecholamines are synthesized in the medulla of the adrenal gland and by some neurons of the central nervous system. The precise location of Pnmt action in the brain and its physiological significance are unknown. Prior studies led by Aaron Owji, a graduate student in Dr. Ebert�s laboratory, showed that mice with selectively ablated Pnmt cells show signs of...
Show morePhenylethanolamine-N-methyltransferase (Pnmt) is the enzyme that catalyzes the conversion of noradrenaline to adrenaline. These catecholamines are synthesized in the medulla of the adrenal gland and by some neurons of the central nervous system. The precise location of Pnmt action in the brain and its physiological significance are unknown. Prior studies led by Aaron Owji, a graduate student in Dr. Ebert�s laboratory, showed that mice with selectively ablated Pnmt cells show signs of neurological defects such as abnormal gait, weakened grip strength, lack of balance, reduced movement, and defective reflexes during tail suspension tests. The cerebellum is a small section of the brain that is responsible for fine-tuning motor commands. Since the Purkinje cells of the cerebellum act as the sole source of output from the cerebellar cortex, impairment of these cells could possibly account for the motor deficits seen in the mice models. The purpose of this project is to determine if there is indeed a change in Purkinje cells between wild type mice and Pnmt-ablated mice. The first aim is to identify quantitative differences in cell count between both genotypes. The second aim is to determine any morphological changes in the Purkinje cells. The main technique used in this project is immunohistochemistry in which cerebellum tissue from mice models are stained with Calbindin (a cellular marker for Purkinje neurons) and imaged with a confocal microscope. Results showed a slight reduction in the Purkinje cells of the ablated mice compared to the control genotype, accompanied with observable differences in cell structure. Understanding catecholamine pathway mechanisms in the nervous system is imperative for elucidating and targeting key players in neurodegenerative disorders.
Show less - Date Issued
- 2016
- Identifier
- CFH2000053, ucf:45511
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH2000053
- Title
- EXAMINING THE RELATIONSHIP BETWEEN FEMALE PARENTS WITH LOW PERCEIVED CONTROL AND ADOLESCENT CHILD STRESS.
- Creator
-
Monaghan, Brendan, Sims, Valerie, University of Central Florida
- Abstract / Description
-
Adolescence is a stressful time for many children. Changes in their environment or changes in social situations are some typical stressors that an adolescent child might encounter. Interactions with parents can also be a stressor for a child. Previous research has shown that a risk factor for a parent using harsh parenting techniques is perceived control. Parents who have low perceived control are at a higher risk to engage in physical parenting techniques or child abuse. This study included...
Show moreAdolescence is a stressful time for many children. Changes in their environment or changes in social situations are some typical stressors that an adolescent child might encounter. Interactions with parents can also be a stressor for a child. Previous research has shown that a risk factor for a parent using harsh parenting techniques is perceived control. Parents who have low perceived control are at a higher risk to engage in physical parenting techniques or child abuse. This study included 198 middle school students and their female parent or guardian pairs (296 total participants), with the adolescent participants ranging in age from 10-year-old to 14-years-old. The adult participants were evaluated for their level of perceived control and the adolescent participants were evaluated for their level of perceived stress. The results showed that parents who perceived themselves as have a low amount of control over their child's behavior (low ACF), regardless of the level of control the parents perceived the child to have over their own behavior (CCF), were linked with their child have a high level of perceived stress, F (1, 182) = 5.14, p = .025. This effect was found only for the 14-year-old participants, t (30) = 2.774, p = .009. Implications of thesis results and areas of further research are suggested. It is possible that as a child gets older and enters puberty, the parent of the child feels as if they are losing control over their child and, as a result, resort to more forceful parenting techniques to regain control.
Show less - Date Issued
- 2011
- Identifier
- CFH0003830, ucf:44751
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0003830
- Title
- Navigation of an Autonomous Differential Drive Robot for Field Scouting in Semi-structured Environments.
- Creator
-
Freese, Douglas, Xu, Yunjun, Lin, Kuo-Chi, Kauffman, Jeffrey L., Behal, Aman, University of Central Florida
- Abstract / Description
-
In recent years, the interests of introducing autonomous robots by growers into agriculture fields are rejuvenated due to the ever-increasing labor cost and the recent declining numbers of seasonal workers. The utilization of customized, autonomous agricultural robots has a profound impact on future orchard operations by providing low cost, meticulous inspection. Different sensors have been proven proficient in agrarian navigation including the likes of GPS, inertial, magnetic, rotary...
Show moreIn recent years, the interests of introducing autonomous robots by growers into agriculture fields are rejuvenated due to the ever-increasing labor cost and the recent declining numbers of seasonal workers. The utilization of customized, autonomous agricultural robots has a profound impact on future orchard operations by providing low cost, meticulous inspection. Different sensors have been proven proficient in agrarian navigation including the likes of GPS, inertial, magnetic, rotary encoding, time of flight as well as vision. To compensate for anticipated disturbances, variances and constraints contingent to the outdoor semi-structured environment, a differential style drive vehicle will be implemented as an easily controllable system to conduct tasks such as imaging and sampling.In order to verify the motion control of a robot, custom-designed for strawberry fields, the task is separated into multiple phases to manage the over-bed and cross-bed operation needs. In particular, during the cross-bed segment an elevated strawberry bed will provide distance references utilized in a logic filter and tuned PID algorithm for safe and efficient travel. Due to the significant sources of uncertainty such as wheel slip and the vehicle model, nonlinear robust controllers are designed for the cross-bed motion, purely relying on vision feedback. A simple image filter algorithm was developed for strawberry row detection, in which pixels corresponding to the bed center will be tracked while the vehicle is in controlled motion. This incorporated derivation and formulation of a bounded uncertainty parameter that will be employed in the nonlinear control. Simulation of the entire system was subsequently completed to ensure the control capability before successful validation in multiple commercial farms. It is anticipated that with the developed algorithms the authentication of fully autonomous robotic systems functioning in agricultural crops will provide heightened efficiency of needed costly services; scouting, disease detection, collection, and distribution.
Show less - Date Issued
- 2018
- Identifier
- CFE0007401, ucf:52743
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007401
- Title
- Nonlinear Control Synthesis for Facilitation of Human-Robot Interaction.
- Creator
-
Ding, Zhangchi, Behal, Aman, Pourmohammadi Fallah, Yaser, Haralambous, Michael, Boloni, Ladislau, Xu, Yunjun, University of Central Florida
- Abstract / Description
-
Human-robot interaction is an area of interest that is becoming increasingly important in robotics research. Nonlinear control design techniques allow researchers to guarantee stability, performance, as well as safety, especially in cases involving physical human-robot interaction (PHRI). In this dissertation, we will propose two different nonlinear controllers and detail the design of an assistive robotic system to facilitate human-robot interaction. In Chapter 2, to facilitate physical...
Show moreHuman-robot interaction is an area of interest that is becoming increasingly important in robotics research. Nonlinear control design techniques allow researchers to guarantee stability, performance, as well as safety, especially in cases involving physical human-robot interaction (PHRI). In this dissertation, we will propose two different nonlinear controllers and detail the design of an assistive robotic system to facilitate human-robot interaction. In Chapter 2, to facilitate physical human-robot interaction, the problem of making a safe compliant contact between a human and an assistive robot is considered. Users with disabilities have a need to utilize their assistive robots for physical interaction during activities such as hair-grooming, scratching, face-sponging, etc. Specifically, we propose a hybrid force/velocity/attitude control for our physical human-robot interaction system which is based on measurements from a force/torque sensor mounted on the robot wrist. While automatically aligning the end-effector surface with the unknown environmental (human) surface, a desired commanded force is applied in the normal direction while following desired velocity commands in the tangential directions. A Lyapunov based stability analysis is provided to prove both convergence as well as passivity of the interaction to ensure both performance and safety. Simulation as well as experimental results verify the performance and robustness of the proposed hybrid force/velocity/attitude controller in the presence of dynamic uncertainties as well as safety compliance of human-robot interactions for a redundant robot manipulator.Chapter 3 presents the design, analysis, and experimental implementation of an adaptive control enabled intelligent algorithm to facilitate 1-click grasping of novel objects by a robotic gripper since one of the most common types of tasks for an assistive robot is pick and place/object retrieval tasks. But there are a variety of objects in our daily life all of which need different optimal force to grasp them. This algorithm facilitates automated grasping force adjustment. The use of object-geometry free modeling coupled with utilization of interaction force and slip velocity measurements allows for the design of an adaptive backstepping controller that is shown to be asymptotically stable via a Lyapunov-based analysis. Experiments with multiple objects using a prototype gripper with embedded sensing show that the proposed scheme is able to effectively immobilize novel objects within the gripper fingers. Furthermore, it is seen that the adaptation allows for close estimation of the minimum grasp force required for safe grasping which results in minimal deformation of the grasped object.In Chapter 4, we present the design and implementation of the motion controllerand adaptive interface for the second generation of the UCF-MANUSintelligent assistive robotic manipulator system. Based on usability testingfor the system, several features were implemented in the interface thatcould reduce the complexity of the human-robot interaction while alsocompensating for the deficits in different human factors, such as WorkingMemory, Response Inhibition, Processing Speed; , Depth Perception, SpatialAbility, Contrast Sensitivity. For the controller part, we designed severalnew features to provide the user has a less complex and safer interactionwith the robot, such as `One-click mode', `Move suggestion mode' and`Gripper Control Assistant'. As for the adaptive interface design, wedesigned and implemented compensators such as `Contrast Enhancement',`Object Proximity Velocity Reduction' and `Orientation Indicator'.
Show less - Date Issued
- 2019
- Identifier
- CFE0007798, ucf:52360
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007798
- Title
- Forward Osmosis for Algae Dewatering and Electrical Field-driven Membrane Fouling Mitigation.
- Creator
-
Munshi, Faris, Lee, Woo Hyoung, Duranceau, Steven, Sadmani, A H M Anwar, Chumbimuni Torres, Karin, University of Central Florida
- Abstract / Description
-
Efficient and low-energy microalgae harvesting is essential for sustainable biofuel production. Forward osmosis (FO) can provide a potential alternative for algae separation with low energy consumption by using osmotic pressure. In this study, an aquaporin-based polyethersulfone (PES) membrane was evaluated for algae dewatering using FO with three different types of draw solutions (DSs: NaCl, KCl and NH4Cl), and under different cross flow velocities (CFVs). 81% of algae dewatering was...
Show moreEfficient and low-energy microalgae harvesting is essential for sustainable biofuel production. Forward osmosis (FO) can provide a potential alternative for algae separation with low energy consumption by using osmotic pressure. In this study, an aquaporin-based polyethersulfone (PES) membrane was evaluated for algae dewatering using FO with three different types of draw solutions (DSs: NaCl, KCl and NH4Cl), and under different cross flow velocities (CFVs). 81% of algae dewatering was achieved with a 29% flux drop. Among three different DSs, although NH4Cl was the best candidate for improved water flux and low reverse salt flux (RSF), it could accelerate cell division, reducing settleability during the FO process. However, RSF originated from NaCl could increase lipid content (~ 49%) in algal biomass probably due to the osmotic imbalance in algal cells. During FO operations, membrane fouling would be an inherent problem against sustainable algae dewatering. In this study, a novel approach was investigated by coupling the FO with an electric field for developing repulsion forces that can prolong the filtration cycle and mitigate foulant attachment. Several electric fields (0.33, 0.13 and 0.03 V mm-1) were applied in continuous and pulsing modes (10sec intervals) to mitigate membrane fouling for effective algae dewatering. The electric field FO configuration used in this study was able to produce 3.8, 2.2 and 2.2 times greater flux at the applied potential of -1.0, -0.4, and -0.1 V, respectively, compared to the control (without an electric field). A high potential of -10 V for 60 sec was applied as an optimal cleaning procedure with a high ability to recover flux (99%). The study also investigated the effect of the electric fields on bulk pH, conductivity, settling velocity, lipid content and microalgal morphology. Overall, this study demonstrates a novel technology for algae dewatering in FO application using the aquaporin-based PES membrane.
Show less - Date Issued
- 2019
- Identifier
- CFE0007507, ucf:52632
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007507
- Title
- I Decide when You Die: A Mixed-Methods Analysis of Prior Reporting of Physical Violence for Intimate Partner Homicides by Heterosexual Spouses in Florida.
- Creator
-
King, Donna, Huff-Corzine, Lin, Reckdenwald, Amy, Corzine, Harold, Bernier, Barbara, University of Central Florida
- Abstract / Description
-
It is generally believed that a victim of an intimate partner homicide, who faced ongoing physical violence prior to the killing, would have contacted authorities for assistance or protection some time prior to their death. However, the results of this study show that this notion that a victim of ongoing abuse will, more than likely, request help is a misconception. Through qualitative and quantitative methods analysis, this study reveals the dearth of prior reporting of physical violence to...
Show moreIt is generally believed that a victim of an intimate partner homicide, who faced ongoing physical violence prior to the killing, would have contacted authorities for assistance or protection some time prior to their death. However, the results of this study show that this notion that a victim of ongoing abuse will, more than likely, request help is a misconception. Through qualitative and quantitative methods analysis, this study reveals the dearth of prior reporting of physical violence to law enforcement or the court when an intimate partner homicide takes place between heterosexual spouses in Florida between 2006 and 2016. Additionally, (")coercive control,(") a term that is not nearly as recognizable as domestic violence or intimate partner violence but that should be understood and regulated, was conceptualized and operationalized using NVivo Pro 12, a qualitative social sciences software package. By constructing an original data set from secondary data from the Florida Department of Law Enforcement Uniform Crime Report Supplemental Homicide Report, multiple law enforcement agencies from throughout the state of Florida, and many Florida county courthouses, variables of intimate partner homicide were analyzed in unique quantitative models using IBM SPSS(&)#174;, an advanced statistical software analysis program. Also, as part of the content analysis process, Petitions for Injunction for Protection against Domestic Violence were organized, coded, and analyzed to provide insight into the role coercive control takes prior to an intimate partner homicide. This study sheds light on the fact that the emphasis on physical violence in intimate partner abuse, rather than the non-violent tactics of coercive control, for lethality risk assessments for intimate partner violence victims is misplaced and warrants reconsideration.
Show less - Date Issued
- 2019
- Identifier
- CFE0007664, ucf:52487
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007664
- Title
- Compiler Design of a Policy Specification Language for Conditional Gradual Release.
- Creator
-
Kashyap Harinath, Manasa, Leavens, Gary, Turgut, Damla, Wang, Liqiang, University of Central Florida
- Abstract / Description
-
Securing the confidentiality and integrity of information manipulated by computer software is an old yet increasingly important problem. Current software permission systems present on Android or iOS provide inadequate support for developing applications with secure information flow policies. To be useful, information flow control policies need to specify declassifications and the conditions under which declassification must occur. Having these declassifications scattered all over the program...
Show moreSecuring the confidentiality and integrity of information manipulated by computer software is an old yet increasingly important problem. Current software permission systems present on Android or iOS provide inadequate support for developing applications with secure information flow policies. To be useful, information flow control policies need to specify declassifications and the conditions under which declassification must occur. Having these declassifications scattered all over the program makes policies hard to find, which makes auditing difficult. To overcome these challenges, a policy specification language, 'Evidently' is discussed that allows one to specify information flow control policies separately from the program and which supports conditional gradual releases that can be automatically enforced. I discuss the Evidently grammar and modular semantics in detail. Finally, I discuss the implementational details of Evidently compiler within the Xtext language development environment and the implementation's enforcement of policies.
Show less - Date Issued
- 2018
- Identifier
- CFE0007205, ucf:52274
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007205
- Title
- State Gun Control Laws.
- Creator
-
Lafleur, Jacob, Huff-Corzine, Lin, Corzine, Harold, Reckdenwald, Amy, University of Central Florida
- Abstract / Description
-
The gun control debate has been placed at the forefront of American politics, as some of the most deadly mass shootings have happened in the last year. Much of the research on the effectiveness of gun control laws have shown inconsistent results. The purpose of the study is to compare states with stricter gun laws to states with more lax laws. This in turn will allow policy makers to identify effective strategies to implement in states that are lacking effective laws. The study examined state...
Show moreThe gun control debate has been placed at the forefront of American politics, as some of the most deadly mass shootings have happened in the last year. Much of the research on the effectiveness of gun control laws have shown inconsistent results. The purpose of the study is to compare states with stricter gun laws to states with more lax laws. This in turn will allow policy makers to identify effective strategies to implement in states that are lacking effective laws. The study examined state gun laws for all 50 states using the Gifford's Law Center to Prevent Gun Violence. The laws that were examined in this study were background checks, license requirements, mental health reporting, wait periods, concealed carry requirements, open carry, disarming prohibited people, and disarming domestic abusers. The states were then given a letter grade based on the laws that they have implemented. The results show that many states have failed to implement any sort of laws that would take guns out of the hands or prevent prohibited people from accessing guns. This study helps identify what laws each state has implemented to control guns throughout their state. This is important because states that are lacking laws in any area can identify and implement effective strategies that other states have put in place.
Show less - Date Issued
- 2018
- Identifier
- CFE0007035, ucf:51985
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007035
- Title
- Prescription Drug Misuse among College Students: An Examination of Sociological Risk Factors.
- Creator
-
Watkins, William, Ford, Jason, Jasinski, Jana, Wright, James, Childs, Kristina, University of Central Florida
- Abstract / Description
-
Prescription drug misuse (PDM), defined as use without a prescription or solely for the feeling or experience caused by the drug, has become a popular topic among substance use researchers. While the vast majority of studies on the topic tackle epidemiological questions surrounding PDM, there is a notable lack of studies that look specifically at risk factors rooted in sociological/criminological theories. The current research seeks to bridge this gap in the literature by examining...
Show morePrescription drug misuse (PDM), defined as use without a prescription or solely for the feeling or experience caused by the drug, has become a popular topic among substance use researchers. While the vast majority of studies on the topic tackle epidemiological questions surrounding PDM, there is a notable lack of studies that look specifically at risk factors rooted in sociological/criminological theories. The current research seeks to bridge this gap in the literature by examining theoretically based explanations for PDM among college students utilizing three criminological theories commonly applied to other forms of substance use: Social Learning Theory, Social Bonding/Control theory, and General Strain Theory. Inaddition, this study also seeks to examine differences in user types characterized by motives for misuse as they relate to predictors stemming from these theories of interest. Utilizing an independently collected sample of 841 college undergraduates from a large southern university, the findings show that nearly one in four students misused prescription drugs in the past semester. Motivations for PDM were primarily instrumental in nature, with very few respondents misusing solely for recreational purposes. Furthermore, social learning based risk factors could best account for PDM within the sample with partial and indirect supports also found for strain based risk factors as well. Implications of these findings as well as theoretical and practical applications are presented.
Show less - Date Issued
- 2012
- Identifier
- CFE0004455, ucf:49341
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004455
- Title
- Italian-American Ethnic Concentration, Informal Social Control, and Urban Violent Crime: A Defended Neighborhoods Approach.
- Creator
-
Marshall, Hollianne, Corzine, Harold, Huff-Corzine, Lin, Jasinski, Jana, Jarvis, John, University of Central Florida
- Abstract / Description
-
This study examines the impact of white ethnic concentration on robbery and homicide in Chicago and New York City. As one of the first to disaggregate white ethnic populations, this study has the expectation that Italian-American concentration will have a stronger influence on robbery and homicide than any other white ethnic concentrations. This study is founded on prior qualitative research suggesting that the reputation of Italian-Americans influences the behavior of outsiders in their...
Show moreThis study examines the impact of white ethnic concentration on robbery and homicide in Chicago and New York City. As one of the first to disaggregate white ethnic populations, this study has the expectation that Italian-American concentration will have a stronger influence on robbery and homicide than any other white ethnic concentrations. This study is founded on prior qualitative research suggesting that the reputation of Italian-Americans influences the behavior of outsiders in their communities. The data show there is a significant and negative relationship between Italian-American concentration and the violent crimes robbery and homicide. This relationship only exists for white ethnic concentration with robbery. These patterns occur across both cities at three different aggregate levels. The results indicate that there may be particular characteristics about Italian-American ethnic concentrations which have dampening effects on the frequency of homicide and robbery in their communities; it is speculated that a reputation for Mafia involvement is one of the protective factors.
Show less - Date Issued
- 2012
- Identifier
- CFE0004407, ucf:49404
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004407
- Title
- STRUCTURAL ANALYSIS AND ACTIVE VIBRATION CONTROL OF TETRAFORM SPACE FRAME FOR USE IN MICRO-SCALE MACHINING.
- Creator
-
Knipe, Kevin, Xu, Chengying, University of Central Florida
- Abstract / Description
-
This research thesis aims to achieve the structural analysis and active vibration damping of the Tetraform machining structure. The Tetraform is a space frame made up of four equilateral triangles with spherical masses at the four vertices. This frame was originally developed for grinding of optical lenses and is now being adapted for use in micro-precision milling. The Tetraform is beneficial to the milling process due to its exceptionally high dynamic stiffness characteristics, which...
Show moreThis research thesis aims to achieve the structural analysis and active vibration damping of the Tetraform machining structure. The Tetraform is a space frame made up of four equilateral triangles with spherical masses at the four vertices. This frame was originally developed for grinding of optical lenses and is now being adapted for use in micro-precision milling. The Tetraform is beneficial to the milling process due to its exceptionally high dynamic stiffness characteristics, which increases the machining stability and allows for higher material removal rates and accuracy. However, there are still some modes of vibration that are critical to the milling process and need to be dampened out. Under operating conditions of many structures, resonant modes of vibration can easily be excited which often lead to structural failure or significant reduction in operating performance. For the milling application, resonant frequencies of the machining structure can severely limit the milling process. The goal of the presented research is to increase surface and subsurface integrity with optimal material removal rate and least possible machining vibration, while maintaining accurate precision and surface finish. The vibrations from the machine tool not only affect the quality of the machined part but also the machine tool itself, since the cutting tool is susceptible to break or wear quickly when operating at high vibration modes, thus inevitably decreasing tool life. Vibration control has gained considerable attention in many areas including aerospace, automotive, structural, and manufacturing. Positive Position Feedback (PPF) is a vibration control scheme that is commonly used for its robust stability properties. A PPF controller works as a low pass filter, eliminating instability from unmodeled higher-frequency modes. The PPF controller concept is used in developing an active vibration control scheme to target the critical frequencies of the Tetraform. The controller is implemented with use of piezoelectric actuators and sensors, where the sensors are bonded to the opposing sides of the beams as the actuators, allowing for the assumption of collocation. The sensor/actuator pairs are placed at an optimal location on the Tetraform with high modal displacements for all the critical frequencies. Multiple finite element models are developed in order to analyze the structural dynamics and allow for controller design. A model is developed in the finite element software ANSYS and is used to obtain the Tetraform's dynamic characteristics, which include natural frequencies and mode shapes. This model is also used to visualize the changes in mode shapes due to structural modifications or different material selections. Other models are also developed in Matlab and Simulink. This consists of the creation of a finite element model which is then converted to state space. The piezoelectric transducers are included in this model for the input and output of the state space model. This model can be used for controller design where the goal is to create maximum decibel reduction at critical frequencies while attempting to minimize controller effort.
Show less - Date Issued
- 2009
- Identifier
- CFE0002962, ucf:47976
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002962
- Title
- DETECTING VARIOUS BURIAL SCENARIOS IN A CONTROLLED SETTING USING GROUND-PENETRATING RADAR AND CONDUCTIVITY.
- Creator
-
Martin, Michael, Schultz, John, University of Central Florida
- Abstract / Description
-
The use of geophysical tools to locate clandestine burials involving bodies has seen increasing popularity among forensic personnel. Often, these search methods are important to highlight certain areas where a body may or may not be located prior to utilizing invasive search techniques. Because of the success of these tools within real-life forensic searches, the use of controlled studies that monitor and detect cadavers over certain lengths of time have been increasingly utilized. However,...
Show moreThe use of geophysical tools to locate clandestine burials involving bodies has seen increasing popularity among forensic personnel. Often, these search methods are important to highlight certain areas where a body may or may not be located prior to utilizing invasive search techniques. Because of the success of these tools within real-life forensic searches, the use of controlled studies that monitor and detect cadavers over certain lengths of time have been increasingly utilized. However, these controlled studies have not monitored various burial scenarios that mimic real-life situations. This study focused on detecting and monitoring six burials containing pig carcasses used as proxies for human bodies and two control burials with a conductivity meter and ground-penetrating radar (GPR) with a 500-MHz and a 250-MHz antenna over a twelve month period. Each burial within this study represented a different forensic scenario that mimicked a real-life situation. Further, forensic use of GPR in both controlled settings as well as real-life searches have mainly focused on the use of a 500-MHz antenna. Therefore, this research also compared the use of a 250-MHz antenna with a 500-MHz antenna. Lastly, a number of GPR imagery options were utilized including reflection profiles and horizontal slices with various GPR software programs to compare the results obtained. Results obtained from the conductivity meter were compared to the results obtained by both antennae of the GPR. Overall, the use of multiple GPR imagery options provided increased resolution of the burial scenarios. Results showed that the conductivity meter was not a beneficial geophysical tool because none of the burial scenarios were detected. On the other hand, the use of GPR showed that the graves with objects added to the pig carcasses provided increased resolution compared to the graves containing only pig carcasses. Lastly, the 250-MHz antenna provided better resolution of the burial scenarios than the 500-MHz antenna due to easier discrimination of the forensic targets. Therefore, the use of a 250-MHz antenna would be a viable option to search for clandestine burials containing adult-sized bodies.
Show less - Date Issued
- 2010
- Identifier
- CFE0003067, ucf:48325
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003067
- Title
- CONTROL OF NONHOLONOMIC SYSTEMS.
- Creator
-
Yuan, Hongliang, Qu, Zhihua, University of Central Florida
- Abstract / Description
-
Many real-world electrical and mechanical systems have velocity-dependent constraints in their dynamic models. For example, car-like robots, unmanned aerial vehicles, autonomous underwater vehicles and hopping robots, etc. Most of these systems can be transformed into a chained form, which is considered as a canonical form of these nonholonomic systems. Hence, study of chained systems ensure their wide applicability. This thesis studied the problem of continuous feed-back control of the...
Show moreMany real-world electrical and mechanical systems have velocity-dependent constraints in their dynamic models. For example, car-like robots, unmanned aerial vehicles, autonomous underwater vehicles and hopping robots, etc. Most of these systems can be transformed into a chained form, which is considered as a canonical form of these nonholonomic systems. Hence, study of chained systems ensure their wide applicability. This thesis studied the problem of continuous feed-back control of the chained systems while pursuing inverse optimality and exponential convergence rates, as well as the feed-back stabilization problem under input saturation constraints. These studies are based on global singularity-free state transformations and controls are synthesized from resulting linear systems. Then, the application of optimal motion planning and dynamic tracking control of nonholonomic autonomous underwater vehicles is considered. The obtained trajectories satisfy the boundary conditions and the vehicles' kinematic model, hence it is smooth and feasible. A collision avoidance criteria is set up to handle the dynamic environments. The resulting controls are in closed forms and suitable for real-time implementations. Further, dynamic tracking controls are developed through the Lyapunov second method and back-stepping technique based on a NPS AUV II model. In what follows, the application of cooperative surveillance and formation control of a group of nonholonomic robots is investigated. A designing scheme is proposed to achieves a rigid formation along a circular trajectory or any arbitrary trajectories. The controllers are decentralized and are able to avoid internal and external collisions. Computer simulations are provided to verify the effectiveness of these designs.
Show less - Date Issued
- 2009
- Identifier
- CFE0002683, ucf:48220
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002683
- Title
- A NEW DEVELOPMENT OF FEEDBACK CONTROLLER FOR LEFT VENTRICULAR ASSIST DEVICE.
- Creator
-
Wang, Yu, Simaan, Marwan, University of Central Florida
- Abstract / Description
-
The rotary Left Ventricular Assist Device (LVAD) is a mechanical pump surgically implanted in patients with end-stage congestive heart failure to help maintain the flow of blood from the sick heart. The rotary type pumps are controlled by varying the impeller speed to control the amount of blood flowing through the LVAD. One important challenge in using these devices is to prevent the occurrence of excessive pumping of blood from the left ventricle (known as suction) that may cause it to...
Show moreThe rotary Left Ventricular Assist Device (LVAD) is a mechanical pump surgically implanted in patients with end-stage congestive heart failure to help maintain the flow of blood from the sick heart. The rotary type pumps are controlled by varying the impeller speed to control the amount of blood flowing through the LVAD. One important challenge in using these devices is to prevent the occurrence of excessive pumping of blood from the left ventricle (known as suction) that may cause it to collapse due to the high pump speed. The development of a proper feedback controller for the pump speed is therefore crucial to meet this challenge. In this thesis, some theoretical and practical issues related to the development of such a controller are discussed. First, a basic nonlinear, time-varying cardiovascular-LVAD circuit model that will be used to develop the controller is reviewed. Using this model, a suction index is tested to detect suction. Finally we propose a feedback controller that uses the pump flow signal to regulate the pump speed based on the suction index and an associated threshold. The objective of this controller is to continuously update the pump speed to adapt to the physiological changes of the patient while at the same time avoiding suction. Simulation results are presented under different conditions of the patient activities. Robustness of the controller to measurement noise is also discussed.
Show less - Date Issued
- 2010
- Identifier
- CFE0003296, ucf:48497
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003296
- Title
- THE CONTRIBUTION OF PROFESSIONAL SCHOOL COUNSELORS' SOCIAL-COGNITIVE DEVELOPMENT TO THEIR LEVELS OF ETHICAL AND LEGAL KNOWLEDGE, AND LOCUS-OF-CONTROL ORIENTATION.
- Creator
-
Ieva, Kara, Lambie, Glenn, University of Central Florida
- Abstract / Description
-
Professional School Counselors (PSCs) are to serve as advocates for all students and promote systemic change (American School Counselor Association, 2008) while navigating complex work environments. The primary purpose of this study was to investigate the contribution of PSCsÂ...
Show moreProfessional School Counselors (PSCs) are to serve as advocates for all students and promote systemic change (American School Counselor Association, 2008) while navigating complex work environments. The primary purpose of this study was to investigate the contribution of PSCsÂÂÂÂÂÂ' social-cognitive development to their levels of ethical and legal knowledge and locus of control orientation. The three constructs and instruments investigated in this study were: (a) social-cognitive development (ego development; the Washington University Sentence Completion Test ; Hy & Loevinger 1996), (b) Ethical and Legal Knowledge (the Ethical and Legal Knowledge in Counseling Questionnaire-Revised ; Lambie, Ieva, Gill, & Hagedorn, 2010), and (c) Locus of Control (the Adult Nowicki-Strickland Internal External Scale- College ; Nowicki & Duke, 1974; the Work Locus of Control Scale ; Spector, 1988). The findings from this investigation contribute to the school counseling and counselor education literature. The sample size for this study was 301 certified, practicing school counselors (elementary school, middle school, high school, and multi-level) in five states (Colorado, Florida, Maine, Maryland, and New Mexico) across the country. The participants completed data collection packets including a general demographic questionnaire, the WUSCT (Hy & Loevinger 1996), the ANSIE-C (Nowicki & Duke, 1974), the WLCS (Spector, 1988), and the ELICQ-R (Lambie, et al., 2010). The statistical procedures used to analyze the data included (a) structural equation modeling (path Analysis), (b) simultaneous multiple regression, (c) Pearson product-moment (2-tailed), and (d) Analysis of variance (ANOVA). The primary research hypothesis was that practicing school counselorsÂÂÂÂÂÂ' social-cognitive development scores would contribute to their locus of control orientation and their levels of ethical and legal knowledge. The statistical analyses identified several significant findings. First, the path analysis model testing the contribution of school counselorsÂÂÂÂÂÂ' social-cognitive development to locus of control and ethical and legal knowledge did fit for these data. Specifically, the results indicated that school counselorsÂÂÂÂÂÂ' social-cognitive development contributed to their ethical and legal knowledge (less than 1% of the variance explained) and to locus of control (14% of the variance explained) in the model fit for these data. In addition, locus of control contributed to school counselorsÂÂÂÂÂÂ' ethical and legal knowledge (2% of the variance explained). Implications for professional school counseling and counselor education are presented, along with areas for future investigation.
Show less - Date Issued
- 2010
- Identifier
- CFE0003150, ucf:48642
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003150
- Title
- VISION BASED TRAJECTORY TRACKING OF SPACE DEBRIS IN CLOSE PROXIMITY VIA INTEGRATED ESTIMATION AND CONTROL.
- Creator
-
Li, Ni, Xu, Yunjun, University of Central Florida
- Abstract / Description
-
The increasingly cluttered environment in space is placing a premium on techniques capable of tracking and estimating the trajectory of space debris. Unlike the debris smaller than 1 cm or larger than 10 cm, it is always a challenge for spacecraft or satellite mission designers to consider explicitly the ones ranged from 1 cm to 10 cm a priori. To tackle this challenge, a vision based debris' trajectory tracking method in close proximity using two cameras onboard satellites in a formation is...
Show moreThe increasingly cluttered environment in space is placing a premium on techniques capable of tracking and estimating the trajectory of space debris. Unlike the debris smaller than 1 cm or larger than 10 cm, it is always a challenge for spacecraft or satellite mission designers to consider explicitly the ones ranged from 1 cm to 10 cm a priori. To tackle this challenge, a vision based debris' trajectory tracking method in close proximity using two cameras onboard satellites in a formation is presented in the thesis. Also to differentiate the target debris from other clutters, data association is investigated. A two-stage nonlinear robust controller is developed to adjust the attitude of the satellites such that the desired field of view can be achieved for the target debris. Capabilities of the proposed integrated estimation and control methods are validated in the simulations.
Show less - Date Issued
- 2011
- Identifier
- CFE0003731, ucf:48775
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003731
- Title
- IPCL1- An Interactive Process Control Language.
- Creator
-
Erlandson, Richard A., Bauer, Christian S., Engineering
- Abstract / Description
-
University of Central Florida College of Engineering Thesis; This report documents a Process Control Language. It was written to provide an easy-to-use, user-friendly language to control a manufacturing-type process. It is not assumed the user is proficient or even familiar with any computer languages. The user should be able to grasp the simple set of commands available and begin writing user programs in a short period of time. Emphasis has been placed on error messages to inform the user of...
Show moreUniversity of Central Florida College of Engineering Thesis; This report documents a Process Control Language. It was written to provide an easy-to-use, user-friendly language to control a manufacturing-type process. It is not assumed the user is proficient or even familiar with any computer languages. The user should be able to grasp the simple set of commands available and begin writing user programs in a short period of time. Emphasis has been placed on error messages to inform the user of the type of error and enough information to correct it. The language was written in PDP-11 assembly language and run on a 11/34 computer in the Microcomputer Laboratory at the University of Central Florida.
Show less - Date Issued
- 1985
- Identifier
- CFR0004771, ucf:52983
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFR0004771
- Title
- Feasability analysis of ramp control systems, a simulation approach.
- Creator
-
Popkin, Henry Allen, Klee, Harold, Engineering
- Abstract / Description
-
Florida Technological University College of Engineering Thesis; The ever increasing traffic congestion being experienced on urban freeways has caused attention to be focused on methods for improving traffic operations on these facilities. The reduction or elimination of freeway congestion can be handled in two basic ways: 1) by increasing the freeway's capacity defined as the number of vehicles per unit time that can pass a given point in one lane of the freeway multiplied by the number of...
Show moreFlorida Technological University College of Engineering Thesis; The ever increasing traffic congestion being experienced on urban freeways has caused attention to be focused on methods for improving traffic operations on these facilities. The reduction or elimination of freeway congestion can be handled in two basic ways: 1) by increasing the freeway's capacity defined as the number of vehicles per unit time that can pass a given point in one lane of the freeway multiplied by the number of lanes on the freeway, or 2) by decreasing the traffic loads imposed on these freeways. Monumental costs and adverse public relations are involved in the construction of either new freeways or additional lanes in urban areas to increase freeway capacity. Due to these factors, the move in recent years has been toward decreasing traffic loads to accomplish the goals of reduction or elimination of freeway congestion. In an effort to combat the freeway congestion, traffic researchers have devoted much time and effort to the theoretical and practical aspects of systems in which controlled access is utilized to prevent or reduce congestion caused by traffic demands in excess of freeway operational capacity. Such systems perform the function of 'freeway surveillance and control'. An important aspect of these systems is the control mechanism used for the regulation of the ramp traffic to the freeway. This topic of ramp metering is the subject of this report.
Show less - Date Issued
- 1975
- Identifier
- CFR0003522, ucf:52998
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFR0003522
- Title
- Cardiac Autonomic Control in Patients with Metabolic Syndrome.
- Creator
-
Mitchell, Jonathan, Cassisi, Jeffrey, Bedwell, Jeffrey, Beidel, Deborah, University of Central Florida
- Abstract / Description
-
Metabolic syndrome (MetS) encompasses metabolic abnormalities that substantially increase risk for chronic illnesses. MetS and stress are closely related; the pathophysiology of MetS involves dysregulated stress response in both the physiological and psychological domains. In an effort to further clarify the relationship between metabolic abnormalities and autonomic dysregulation, we used ambulatory impedance cardiography to examine indicators of cardiac autonomic control (CAC) in a sample of...
Show moreMetabolic syndrome (MetS) encompasses metabolic abnormalities that substantially increase risk for chronic illnesses. MetS and stress are closely related; the pathophysiology of MetS involves dysregulated stress response in both the physiological and psychological domains. In an effort to further clarify the relationship between metabolic abnormalities and autonomic dysregulation, we used ambulatory impedance cardiography to examine indicators of cardiac autonomic control (CAC) in a sample of 50 adult primary care patients with and without MetS. Indices of sympathetic and parasympathetic influences on cardiovascular functioning were assessed in the context of psychological stressors and compared across experimental groups and examined in relation to self-reported health measures. Primary results suggest that while our experimental groups did not differ significantly on baseline measures, patterns of responses to experimentally induced stressors were largely consistent with our predictions, and demonstrate that individuals with MetS responded to stress cues with more maladaptive CAC scores. Moreover, in line with previous work, we found that elements of CAC in our sample were predictive of both cardiovascular disease and self-reported environmental quality of life. Overall, our results suggest that maladaptive physiological manifestations of the stress response are evident among individuals with MetS and may also be related to long-term health outcomes. The present study carries implications for both evaluation and assessment as well as treatment delivery and monitoring. In addition, the ambulatory nature of data collection demonstrated here supports trends toward mHealth and related initiatives in emerging modes of healthcare delivery.
Show less - Date Issued
- 2016
- Identifier
- CFE0006359, ucf:51519
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006359
