This dissertation studies the thermodynamic and structural properties of aqueous dispersions of ionic microgels ? soft colloidal particles composed of cross-linked polymer gels that swell in a good solvent. Starting from a coarse-grained model of microgel particles, we perform computer simulations and theoretical calculations using two complementary implementations of Poisson- Boltzmann (PB) theory. Within the framework of a cell model, the nonlinear PB equation is exactly solved and used to compute counterion distributions and osmotic pressures. By varying the free energy with respect to microgel size, we obtain exact statistical mechanical relations for the electrostatic component of the single-particle osmotic pressure. Explicit results are presented for equilibrium swelling ratios of charged microcapsules and of charged cylindrical and spherical microgels with fixed charge uniformly distributed over the surface or volume of the particle. Molecular dynamics simulations validate the theoretical findings. In the second method, within a one-component model framework, based on a linear-response approximation for effective electro- static interactions, we develop Monte Carlo (MC) simulations to compute the equilibrium swelling ratio, bulk osmotic pressure, radial distribution function, and static structure factor. Results presented in this dissertation demonstrate that swelling of ionic microgels increases with increasing microgel charge and decreases with increasing concentration of salt and microgels. In addition, results demonstrate that the microion distributions and osmotic pressure determine equilibrium swelling of microgels. Cell model predictions for bulk osmotic pressure agree well with data from MC simulations of the one-component model. The MC simulations also provide access to structural properties and to swelling behavior of microgels in highly concentrated suspensions. Taken together, results obtained in this work provide insight into factors of importance for practical use of microgels as drug delivery systems, in tissue engineering, and for other biomedical applications.

No description available.

No description available.

No description available.

No description available.

Students with disabilities are highly at-risk for administrative disciplinary actions that remove them from school for misconduct. School leaders have the authority and expertise to reduce the amount of these removals by reconsidering their current methods for discipline, reflecting on how these affect their students, and making changes to student consequences. The purpose of this study was to determine what highly skilled principals in the field have found to be the most effective strategies in reducing or eliminating out-of-school suspensions for students with disabilities. This insight is invaluable to the discussion on next steps to close the discipline gap between special education and regular education students. This study used a Delphi model for research building consensus through three rounds of surveys. This input was collected from a panel of 15 principals from 13 school divisions across Virginia that were identified as having already achieved success in eliminating out-of-school suspensions for students with disabilities. The panel concluded that principals must ensure a positive relationship with every student, use alternative, logical, and authentic consequences, and identify and implement individualized supports and accommodations when addressing student misconduct to eliminate out-of-school suspensions for their students with disabilities. Principals should implement practical strategies that proactively build positive relationships and help them better understand the child as an individual in order to reduce or eliminate suspensions in their schools. / Doctor of Education / Students with disabilities are highly at-risk for administrative disciplinary actions that remove them from school for misconduct. School leaders have the authority and expertise to reduce the amount of these removals by reconsidering their current methods for discipline, reflecting on how these affect their students, and making changes to student consequences. The purpose of this study was to determine what highly skilled principals in the field have found to be the most effective strategies in reducing or eliminating out-of-school suspensions for students with disabilities. This insight is invaluable to the discussion on next steps to close the discipline gap between special education and regular education students. This study used surveys to gather input and find agreement on best practices from a panel of elementary school principals from many school divisions across Virginia. The panel concluded that principals must ensure a positive relationship with every student, use alternative, logical, and authentic consequences, and identify and implement individualized supports and accommodations when addressing student misconduct to eliminate out-of-school suspensions for their students with disabilities. Principals should implement practical strategies that proactively build positive relationships and help them better understand the child as an individual in order to reduce or eliminate suspensions in their schools.

This experimental study evaluates the dynamic response of five semi-active control policies as tested on a single suspension quarter-car system. Incorporating a magneto-rheological damper, the full-scale 2DOF quarter-car system was used to evaluate skyhook, groundhook, and hybrid control. Two alternative skyhook policies were also considered, namely displacement skyhook and relative displacement skyhook. As well as exploring the relative benefits of each of these controllers, the performance of each semi-active controller was compared to the performance of conventional passive damping. Each control policy is evaluated for its control performance under three different base excitations: chirp, step, and pure tone. Corresponding to the chirp input, transmissibilities and auto spectrums are considered for each control policy. Specifically, transmissibilities between the sprung mass displacement and the unsprung mass displacement are generated relative to the input displacement. Further, the ratio between the relative displacement across the damper and the input displacement is evaluated for each control technique. The chirp input also reveals the results of the auto spectrums of the sprung and unsprung mass accelerations. Both the step input and the pure tone input were used to generate time domain values of RMS and peak-to-peak displacements and accelerations. This study shows that semi-active control offers benefits beyond those of conventional passive damping. Further, traditional skyhook control is shown to outperform the less conventional alternative skyhook policies. / Master of Science

The literature shows that school attendance matters. Time engaged with instruction is highly correlated to student achievement (Brophy, 1988; Fisher et al., 2015; Northwest Regional Educational Laboratory, 2001). However, students who are suspended and expelled from school lose instructional time in the classroom (Belway, Hodson, Losen, Keith II, and Morrison, 2015; Scott and Barrett, 2004). Suspensions result in decreased student attendance by removing the student from the learning environment (Noltemeyer, Ward, and Mcloughlin, 2015). The use of in-school suspension (ISS), out-of-school suspension (OSS), and expulsion are referred to as exclusionary discipline (Belway et al., 2015). Educational leaders are unintentionally contributing to the achievement gaps that the No Child Left Behind (NCLB) legislation intended to close by not addressing student suspensions and expulsions (Belway et al., 2015). This study used quantitative data with an ex post facto design to determine if the implementation of school-wide positive behavioral interventions and supports (PBIS) resulted in a change in student absences, office discipline referrals, and suspensions in one middle school and to determine what difference, if any, was there in student absences, office discipline referrals, and suspensions between a school implementing PBIS and a school not implementing PBIS. Two suburban middle schools in one Virginia school division were included in this study. Following the conceptual framework for this study, it was anticipated that implementation of PBIS would decrease student absences, office discipline referrals, and suspensions. The results of the study revealed that there was a reduction in office discipline referrals following the first year of implementation in the PBIS Middle School. When comparing a school that implemented PBIS to one that did not, this study found that student suspensions decreased by the second year of implementation in the school that implemented PBIS. This study also yielded other findings that were inconsistent with existing research. The results of this study are of significance for education leaders who want to decrease student office discipline referrals and suspensions / Ed. D.

This thesis aims at estimating vital vehicle states and developing control algorithms for automotive suspensions and vehicle stability. A parametric model of an automotive monotube damper is developed and several control algorithms for semi-active suspensions have been developed. An extensive comparison of different control algorithms has been done. Skyhook, Groundhook, Hybrid, Acceleration-driven, Power-driven, Groundhook-linear, Linear Quadratic Regulator (LQR) optimal, Genetic algorithm optimized Linear Quadratic Regulator optimal, Model-reference adaptive, H∞ robust, µ-synthesis, fuzzy-logic based, and Deep Reinforcement learning based control algorithms have been developed and simulated. A shock dyno is instrumented and skyhook and groundhook control algorithms have been implemented as well. In addition to this, a semi-active suspension switching based control algorithm is developed for reducing the effort of a direct moment yaw rate controller, and improve stability of a vehicle when turning. Accelerometer based intelligent tires have been used to estimate vehicle states like vertical load on tire, velocity of the vehicle, unsprung mass acceleration, and forces on a tire. All these estimations would be helpful in observing various parameters of a vehicle using data from only a tri-axis accelerometer inside the tire. Data was collected in an instrumented Volkswagen Jetta and a Trailer setup as well. The test vehicle was instrumented with a tri-axis accelerometer inside the tire, encoder, Inertial Measurement Unit (IMU), and VBOX Racelogic Global Positioning System (GPS) based velocity measurement unit. For payload estimation, the data collected by the in-tire accelerometer was converted into frequency domain using Welch's method of averaging, followed by feature extraction. The extracted features were fed to a trained bagged trees model. Root mean squared error of 11% was observed on the test dataset. For velocity estimation, the data collected by the accelerometer was fed to a variational mode decomposition process. The extracted mode was converted to time-frequency domain using Hilbert transform and features for machine learning were extracted. A root mean squared error of 1.02kmph was observed on the trained dataset. A Gaussian process model was trained for this application. For unsprung mass acceleration estimation, the test vehicle was instrumented with an accelerometer near the wheel spindle as well. For this estimation problem, Convolutional neural networks (CNN) were used. The time-frequency spectrogram of x, y, and z axis data of the in-tire accelerometer were considered as the three color channels of an image. With this, an image of 224 x 224 x 3 dimensions was generated, which represented the time and frequency variation of data. These images were used for training the CNN and a 96.8% coefficient of correlation was obtained for this regression task. For the last wheel force estimation problem, the concept of training the images generated by overlapping time-frequency matrices was used and an accuracy of 90.1% was achieved. With these estimation of vehicle states, better control algorithms can be developed and deployed for better handling, safety and comfort of vehicles using data from only tri-axis accelerometer in the tire. / Master of Science / The main objective of this thesis is to aid in the development of better control systems for vehicles, using data from accelerometer-based intelligent tire. Payload on the vehicle's tire, vehicle velocity, wheel acceleration, and wheel forces are vital parameters, which if estimated correctly can be instrumental in having better understanding of the vehicle's condition. A tri-axis accelerometer is mounted inside the tire, and is used for estimating these vehicle parameters. Statistical models are developed based on features extracted from the accelerometer data. The main challenge was to use the data collected by only intelligent tire to estimate vehicle states. This makes the developed algorithms independent of other sensors and hence economic. Tires are the only component which serve as a link between the vehicle and road. Hence, these parameter estimations can be accurately observed simultaneously using the in-tire accelerometer data. Testing is done on an instrumented trailer-test setup and a Volkswagen Jetta. The vehicle is instrumented with the intelligent tire, a Global positioning system (GPS) based velocity measuring unit, Inertial measurement unit (IMU), and encoder. Testing is done for different loading conditions, road surfaces, inflation pressures, and vehicle velocities. In this way, it has been attempted to make the developed statistical models robust and expose them to a multitude of test conditions. In addition to this, several suspension semi-active control algorithms have been developed for improving vehicle ride comfort and road holding. A parametric damper model has been developed, and several control algorithms have been simulated. A shock dyno experimental setup has been instrumented and some of the control algorithms have been implemented. With this, several suspension semi-active control algorithms have been developed, and statistical models have been developed for estimation of various vehicle parameters. This research can be helpful for developing accurate control algorithms for active safety systems in a vehicle.

This analytical study evaluates the response characteristics of a two-degree-of freedom quarter-car model, using passive and semi-active dampers, along with a seven-degree-of-freedom full vehicle model. The behaviors of the semi-actively suspended vehicles have been evaluated using skyhook, groundhook, and hybrid control policies, and compared to the behaviors of the passively-suspended vehicles. The relationship between vibration isolation, suspension deflection, and road-holding is studied for the quarter-car model. Three main performance indices are used as a measure of vibration isolation (which can be seen as a comfort index), suspension travel requirements, and road-holding quality. After performing numerical simulations on a seven-degree-of-freedom full vehicle model in order to confirm the general trends found for the quarter-car model, these three indices are minimized using optimization techniques. The results of this study indicate that the hybrid control policy yields better comfort than a passive suspension, without reducing the road-holding quality or increasing the suspension displacement for typical passenger cars. The results also indicate that for typical passenger cars, the hybrid control policy results in a better compromise between comfort, road-holding and suspension travel requirements than the skyhook and groundhook control policies. Finally, the numerical simulations performed on a seven-degree-of-freedom full vehicle model indicate that the motion of the quarter-car model is not only a good approximation of the heave motion of a full-vehicle model, but also of the pitch and roll motions since both are very similar to the heave motion. / Master of Science