Of the 795,000 people that suffer a stroke in the United States every year, 65% experience hemiparesis. Foot drop is a common gait pathology in people with lower-limb paresis and is often caused by neuropathy of the peroneal nerve that innervates the muscles responsible for ankle dorsiflexion. Foot drop can impede toe clearance and increase the risk of falling, the leading cause of injury among adults ≥65 years. Lower-limb robotic exoskeletons have been used for gait training and can aid with walking, but current devices on the market can be heavy, expensive, and constrained to in-clinic use. Soft wearable robotic devices offer a lightweight and cost-effective alternative to traditional lower-limb exoskeletons. In particular, soft pneumatic systems have the potential to provide a high power-to-weight ratio making them ideal for a wearable application. The soft pneumatic exosuit consists of a footplate to collect air, storage to temporarily house the collected air, and two pneumatic actuators to provide an assistive torque around the wearer’s ankle joint while walking. EMG and IMU sensors were integrated to control the opening and closing of solenoid valves so that assistive torques could be applied to the ankle joint at optimal moments during the gait cycle. Preliminary validation of the soft pneumatic exosuit on a healthy participant demonstrated that the system could successfully deliver the air required to contract the actuators when the EMG sensors detected an increase in muscle activity. These results demonstrate that the current soft pneumatic exosuit appears to be a promising alternative to current rehabilitation exoskeletons on the market while remaining portable and low-cost. / 2025-05-24T00:00:00Z

This thesis studied unpaved highway shoulders, and in particular shoulders of lower volume asphalt pavements being overlaid. The primary objective was to better understand how different shoulder aggregates perform on lower volume routes with asphalt surfaces and relatively narrow shoulders. A literature review and an evaluation of a full-scale test section containing five aggregate categories in nine test sections over a thirty-four-month period were the primary efforts performed to evaluate unpaved highway shoulders. The study concluded shoulder width measurements were not especially informative, and that California Bearing Ratio measurements were only modestly informative. Crushed concrete outperformed all other aggregates, though the remaining aggregate categories (gravel, limestone, steel slag, and reclaimed asphalt pavement) also had a reasonable case for being moved forward toward possible specification updates. The primary recommendation of this thesis is to use the data contained herein to further shoulder aggregate specifications for the Mississippi Department of Transportation.

No description available.

The current study focuses on improving and testing the CTF thermalhydraulics computer code. CTF is a thermalhydraulic code used for subchannel analysis of nuclear power reactors developed as part of the US DOE CASL program and distributed by North Carolina State University. Subchannel analyses are used to predict the local fuel temperatures and coolant conditions inside a complex nuclear fuel assembly. Such calculations are used to improve designs of nuclear fuel, improve operating margins, or perform safety analysis. An important part of the code development process is the verification and validation for its intended use. In this work validation activities are performed using the RISO experiments are modeled in CTF for adiabatic and diabatic cases in annular flow regimes and a limited set of tests in CANDU geometries. The CTF predictions significantly overpredicted the pressure drop for cases involving annular flow conditions. Depending on the application, such overprediction can result in significant errors in the computation of fuel element dryout and other figures of merit. For example, an analysis using fixed pressure boundary conditions CTF predicts much lower subchannel flows and hence fuel element temperatures may be overestimated. On the other hand, for a scenario with mass flux and inlet pressure as boundary conditions, the impact of pressure drop discrepancies on dryout predictions may be lower. Therefore, there is a particular focus in this thesis on the two-phase pressure drop models and the RISO experiment specifically, since the RISO tests involve a range of annular flow conditions which is prototypical of many CANDU accident analysis conditions. In addition to the RISO experiments, 28-element CANDU full scale rod bundle experiments are modeled in CTF for single-phase and two-phase flow conditions. Cases are modeled for crept and uncrept conditions with different bearing pad heights i.e., 1.17 mm and 1.35mm. Pressure drop predictions are compared with the experimental results where single-phase comparisons are in good agreement while an overprediction of ~25% is observed for two-phase conditions. The effect of bearing pads on the subchannel local parameters, like mass flow rate, are also studied. Furthermore, the effect of turbulent mixing rate on subchannel enthalpy distribution in the bundle and CHF in different subchannels is also analyzed. Based on the comparison to the RISO and CANDU 28 element test databases, the overprediction of pressure drop in the annular flow regime needs improvement in the current version of CTF. This overprediction of the frictional pressure drop results from either wall drag or interfacial shear stress phenomena. In this study, it is demonstrated that the issue occurs mostly as a result of interfacial friction factor modelling this work examines several alternative approaches. The results show the Ju’s and Sun’s interfacial friction factor better predicts the results among all the other six correlations implemented in CTF. The major impediment in further testing of CTF is that it lacks the capability to simulate R-134a fluids. Given there is a large database of R-134a two-phase tests, another aspect of this thesis is to extend CTF for application and validation using refrigerants. The current CTF version only supports fluid properties for water and FLiBe salts. By adding R-134a fluid properties the testing and validation range of CTF is broadened for different experiments performed using R-134a fluids. CHF experiments are modeled in CTF and results are compared with experimental data. For local conditions correlation, 2006 water LUT are used to predict CHF and DNBR. The fluid-to-fluid scaling method is applied in CTF when using CTF with R-134a fluid properties for CHF and DNBR predictions to account for the difference in fluid properties between R-134a and the CHF look-up table. / Thesis / Master of Applied Science (MASc) / COBRA-TF (CTF) is a thermalhydraulic code, based on the historical code COBRA-TF, used for subchannel analysis of nuclear power reactors. Subchannel analysis can be used to predict the local fuel temperatures and coolant conditions inside a complex nuclear fuel assembly. CTF is a transient code that simultaneously solves conservation equations for mass, momentum, and energy for the three coolant phases present, i.e. vapor, continuous liquid, and entrained liquid droplet phases. The scope of the current study includes 1) testing the code for conditions relevant to CANDU accident analysis, 2) refinement of the models that are used in two-phase interfacial friction calculations, and 3) inclusion of alternate fluid properties. The testing of CTF is performed with different experimental databases covering CANDU thermalhydraulic conditions. The refinement is done by improving the pressure drop prediction in the annular flow regime by using different interfacial friction factor correlations from earlier studies in the literature. The current CTF version includes water and liquid salt properties (FLiBe) for coolant fluids. Freon (R-134a) fluid properties have been added in CTF in order to broaden the testing range of CTF for different experimental database using R-134a as working fluid.

No description available.

No description available.

The introduction of programmability and dynamic protocol deployment in routers, there would be an increase in the potential vulnerabilities and attacks . The next- generation Internet promises to provide a fundamental shift in the underlying architecture to support dynamic deployment of network protocols. In this thesis, we consider the problem of detecting malicious packet drops in routers. Specifically, we focus on an attack scenario, where a router selectively drops packets destined for another node. Detecting such an attack is challenging since it requires differentiating malicious packet drops from congestion-based packet losses. We propose a controller- based malicious packet detection technique that effectively detects malicious routers using delayed sampling technique and verification of the evidence. The verification involves periodically determining congestion losses in the network and comparing the forwarding behaviors of the adjoining routers to affirm the state of a router in the network. We provide a performance analysis of the detection accuracy and quantify the communication overhead of our system. Our results show that our technique provides accurate detection with low performance overhead.

The problems with which this dissertation is concerned are undergraduate student attrition and ways to reduce it. This study describes the problem of undergraduate student attrition by presenting an overview of the extent of such attrition. As a result of this study, the following conclusions, among others, are advanced: 1) Approximately 50 per cent of those who undertake a baccalaureate degree program complete their programs within four years. 2) Attrition data provide a measure of efficiency of higher education. 3) Undergraduates who do not complete course or degree requirements in either attendance or academic performance contribute to and constitute a measure of waste in the economic sense of (a) the labor of teachers, (b) the use of classrooms, laboratories, and equipment, (c) the failure of colleges and universities to achieve educational objectives, and (d) the competent individuals who never enter college. 4) Attrition is a distinct, interactive process. 5) Institutions of higher learning are responsible for changing their characteristics and environments when such variables adversely affect congruence of otherwise qualified and competent students. 6) Texas' senior college presidents who were surveyed believe that an extremely important variable in reducing attrition is the establishment of a relationship between the student and the institution through a competent, concerned faculty or staff member or peer.

Computer simulation is an essential tool in the development process of childseats, particularly when it comes to ensuring the safety of child passengers.As awareness regarding child passenger safety continues to grow, the use ofsuitable materials in the development of child seats becomes increasinglycrucial. Numerical simulations play a vital role throughout the entiredevelopment phase, enabling accurate analysis and evaluation. Toeffectively reduce development costs and time, it is imperative to have amaterial model that accurately predicts the behavior of materials innumerical simulations. This enables optimized performance of child seatswhile maintaining safety standards. The objective of the thesis is to implement a standard procedure forextracting material data for numerical modelling of foam materials andvalidating it. In this study, material models available in LS-DYNA, such asMAT_083 and MAT_057 for foam materials, are utilized along withcompression test data to create the material model. The model is furtherenhanced by optimizing the material parameters to establish a correlationbetween the test and simulation results. The improved material model is thenvalidated by comparing it with the impact drop test results. However,THULE's current impact drop test equipment is not considered accurate orefficient, and addressing this issue is one of the main objectives of thisthesis. Within this thesis, the identified problems are thoroughly examined,and suitable solutions are proposed to ensure the accurate extraction ofmaterial data and its validation, particularly when introducing new foammaterials.

<div>Rain drop size distributions (DSDs) in severe convective storms are highly variable in time and space. DSDs can be derived from polarimetric radar observations at high spatiotemporal resolution but these observations are often lacking near the surface owing to radar horizon issues. Disdrometers provide “ground-truth” measurements and validation of radar-derived DSDs but are by nature limited point measurements. Moreover, substantial evolution of the DSD can occur between the lowest radar elevation angle and the surface. Recent studies have shown that hydrometeor size sorting (HSS) is an important and even dominant process contributing to DSD evolution in severe storms; many physical processes such as the strength of the updraft, transient effects, and storm-relative mean winds are contributing factors to continued size sorting. In this study, we focus on strong storm-relative mean winds that induce sustained size sorting owing to the different residence times of hydrometeors of different sizes as they fall in severe storms. The resulting differential advection leads to a distinct horizontal spread of hydrometeors of different sizes at the bottom of a given layer. The goal of this study is to evaluate the impact of size sorting on DSD evolution from the radar level to the surface. To accomplish this, we develop and apply a raindrop trajectory model to compute the evolution of DSDs between radar observations aloft and the surface. For simplicity and to isolate the effects of size sorting, we neglect processes such as breakup, collection, and evaporation, and assume a horizontally homogeneous wind profile. We use disdrometer and radar data, which measure DSDs at the surface and provide the observed quantities aloft, respectively. The disdrometer data was collected from portable disdrometers as a collaboration between Purdue University, University of Oklahoma, University of Massachusetts, and the National Severe Storms Laboratory during the VORTEX-SE 2017 field campaign. NEXRAD data from KHTX Huntsville, AL and KGWX Columbus Air Force Base, MS was retrieved from the National Centers for Environmental Information (NCEI).</div><div><br></div><div>We evaluate three separate cases, a tornadic QLCS on 30 April 2017, a cluster storm on 27 March 2017, and a squall line on 25 March 2017. After the radar data is pre-processed, we retrieve the DSDs from the radar by assuming a gamma distribution and discretize them into PARSIVEL bins to produce a gridded dataset of DSDs. We then apply the raindrop trajectory model to compute the DSDs at the surface which are then compared directly with disdrometer observations. Analysis and comparisons from all cases yield similar results in that-the sorted radar DSDs at the surface are overall closer to the disdrometer observations than the original radar DSDs aloft. Results also show that the spatial variation of DSDs is higher at the surface due to size sorting by the storm-relative mean winds.</div><div><br></div>