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Subject-specific Human Knee FEA Models for Transtibial Amputees Vs Control Tibial Cartilage Pressure in Gait, Cycling and Elliptical Training
Get PDFMillions of individuals around the globe are impacted by osteoarthritis, which is the prevailing type of arthritis. This condition arises as a result of gradual deterioration of the protective cartilage that safeguards the ends of the bones. This is especially true of transtibial amputees, who have a significantly higher incidence of osteoarthritis of the knee in their intact limb than non-amputees. Engaging in regular physical activity, managing weight effectively, and undergoing specific treatments can potentially slow down the advancement of the disease and enhance pain relief and joint function. Nevertheless, the relationship between the type of exercise and its impact on cartilage stress remains uncertain. In order to address this question, tibiofemoral finite element analysis (FEA) models were developed. The models incorporated more realistic material properties for cartilage, hexahedral elements, and non-linear springs for ligaments. To ensure their accuracy, the models were validated against experimental data obtained from cadaveric studies. The contact loads and flexion angles of two individuals with amputations and one individual without amputation, which were obtained in a previous study conducted at Cal Poly, were implemented in the FEA models for gait, cycling, and elliptical exercises. The FEA models were used to extract the maximum stress values experienced in the tibial contact areas, specifically in the medial and lateral compartments of the knee. In cycling, the normalized contact pressure on the tibial articular cartilage, relative to body weight, was generally higher for the two participants with amputations compared to the control participant, except for the medial compartment. Furthermore, when comparing different exercises, cycling resulted in the lowest contact pressure values, with elliptical and walking exercises producing similar maximum values. The findings indicated that individuals with amputations are at a greater risk of developing OA, regardless of the type of exercise performed. However, among the different exercises studied, cycling was found to exert the lowest levels of compression stress on the tibial cartilage
Heat Flux Dynamics and Seasonal Variability in Morro Bay, California
Get PDFThere is a growing need to better understand the dynamics of small and medium Mediterranean low-inflow estuaries (LIEs), which is addressed here by characterizing a heat budget and associated heat transfer processes. A one-dimensional deterministic model was developed from the advection-diffusion equation and applied to Morro Bay, CA using 15-minute water property (temperature, salinity, pressure) and meteorological (wind speed and direction, air temperature, relative humidity, air pressure, irradiance) data collected over a two-year period (2020 – 2021). Seasonal variability is observed in meteorological components, water temperature, and salinity. There is strong seasonal variability in head-mouth temperature and salinity differences. Temperature differences peak in summer (daily mean 2.52 ºC, June – Sept.). Daily average salinity difference is 0.33 (hyposaline, Sept. – Apr.) with strongest gradients observed during the winter storm season following enhanced freshwater discharge. Inverse salinity develops intermittently May – Aug. Subtidal heat flux is dominated by surface heating, whose daily average is always positive (heat input). The developed model does not quantify adequate heat export from the estuary, however, a sensitivity analysis indicates that diffusive flux may be a significant heat export component. Excess heat appears to be exported to the ocean, allowing ocean-estuary temperatures to remain similar. Characterizing estuarine dynamics like these enables us to predict how Morro Bay, and other similar estuarine systems, may respond to long and short-term environmental changes, and how these responses influence estuarine circulation and environmental health
Machine Learning Prediction of HEA Properties
Get PDFHigh-entropy alloys (HEA) are a very new development in the field of metallurgical materials. They are made up of multiple principle atoms unlike traditional alloys, which contributes to their high configurational entropy. The microstructure and properties of HEAs are are not well predicted with the models developed for more common engineering alloys, and there is not enough data available on HEAs to fully represent the complex behavior of these alloys. To that end, we explore how the use of machine learning models can be used to model the complex, high dimensional behavior in the HEA composition space. Based on our review and experimentation, the use of a variational autoencoder will allow future research to lower the dimensionality (and therefore complexity) of the HEA composition space and allow for novel alloy generation based on one or more desired properties
Drones for Marine Science and Agriculture
Get PDFOur research project was launched at Cal Poly in 2019 with the goal of assisting researchers at the CSULB Shark Lab in detecting sharks from aerial images. Under the guidance of Dr. Franz J. Kurfess, students trained an object detection algorithm using shark images and were able to achieve high rate of detection. Following this success, the team has constructed multiple drones and expanded their research to include applications in the fields of agriculture and ecology. This summer the goal is to use a iPhone 14 Pro in lieu of a traditional camera system for real-time object recognition. Object detection was found to be achievable on the iPhone 14 Pro through using YOLO which provided good inference times and precision for object recognition. Research was continued looking toward low-cost methods of object recognition, as well as further development using iPhone 14 Pro setting a base for future projects using the device
Validation of Macro Button Toolbar System for Radiology Report Composition
Get PDFThe macro button toolbar system was developed to enhance radiologist report composition and improve group productivity in response to a rise in imaging volume and an impending radiologist workforce shortage. This research aims to validate the proposed benefits of the macro button toolbar system using an analysis of a time study and the radiology group’s historical wRVU productivity data. The study found that radiologists using this system achieved significantly higher productivity compared to national averages, with high toolbar users experiencing a 29% increase in wRVU productivity and a 52.6% reduction in report completion time for X-ray exams. The reduced report completion time for x-ray exams allows radiologists to focus on more complex reports and examinations that do not utilize the macro button toolbar system as fully and therefore increase daily productivity
Gyroless Nanosatellite Attitude Determination Using an Array of Spatially Distributed Accelerometers
Get PDFThe low size and budget of typical nanosatellite missions limit the available sensors for attitude estimation. Relatively high noise MEMS gyroscopes often must be employed when accurate knowledge of the spacecraft’s angular velocity is necessary for attitude determination and control. This thesis derived and tested in simulation the “Virtual Gyroscope” algorithm, which replaced a standard gyroscope with an array of spatially distributed accelerometers for a 1U CubeSat mission. A MEMS accelerometer model was developed and validated using Root Allan Variance, and the Virtual Gyroscope was tested both in the open loop configuration and as a replacement for a gyroscope in a Multiplicative Extended Kalman Filter. It was found that the quality of the Virtual Gyroscope’s rate measurement improved with a larger and higher quality array, but the error in the estimate was very large. The low signal-to-noise ratio and the unknown bias in the accelerometers caused the angular velocity estimate from the accelerometer array to be too poor for use in the propagation step of the Kalman filter. The Kalman filter performed better with attitude measurements alone than with the Virtual Gyroscope, even when the attitude were delivered at a low rate with added noise. Overall, the current Virtual Gyroscope algorithm that is presented in this thesis is not suitable to replace a MEMS gyroscope in a nanosatellite mission, although there is room for future improvements using bias prediction for the individual accelerometers in the array
Mbesese Build 2023
Get PDFIn collaboration with the Mbesese Initiative for Sustainable Developments, the senior project group from California Polytechnic State University of San Luis Obispo, researched, designed, and created construction documents for the Same Polytechnic College project in the town of Same, Tanzania. This project aims to combat poverty in the Kilimanjaro Region of Tanzania by providing education and infrastructure development. In 2023, the senior project group focused on completing a communal and educational space and addressing clean water scarcity through a rainwater collection system on the site of the future college