UWEC CERCA 2025

Organic Light Emitting Diode (OLED) displays use organic compounds to emit light of many different colors on screen technologies. They can produce a wider range of colors and have higher energy efficiency than traditional LEDs. For this research, I will be working with Dr. Radue to investigate OLEDs assembled by Dr. Rybicki’s research group. The OLEDs consist of a glass slide, indium tin oxide (ITO), tris- (8-hydroxyquinoline) aluminum (AlQ3), calcium, and aluminum. Last year’s research revealed that exposing an OLED sample to short wave UV light leads to a reduction in peak transmittance amplitudes. Measurements were taken using Fourier-transform infrared spectroscopy (FTIR), and data from samples exposed and unexposed to UV light was compared and analyzed. Currently, Dr. Radue and I are focusing on changes in magnetoresistance and the IV (current-voltage) curve as the OLED devices are exposed to short wave UV light. If no significant changes occur from the UV light, devices will instead be exposed to an x-ray source. After determining the minimum exposure needed to change magnetoresistance, measurements will be conducted on an uncoated AlQ3 sample exposed to the same amount of radiation. Said measurements will be performed using FTIR, Raman spectroscopy, ellipsometry, and ultraviolet-visible (UV-vis) spectroscopy.

When we look up to the stars, we only see a brief snapshot of the universe’s life. The stars change over the course of many millions of years, making it difficult to observe their behaviors. Consequently, astrophysicists who wish to study the lives of stars turn to computers to model them. This project utilizes Modules for Experimentation in Stellar Astrophysics (MESA), specifically the wd_builder module, to model the behaviors of white dwarf stars. These are the leftovers of average-sized stars, like our Sun, that have reached the ends of their lives and collapsed into hot, dense stellar remnants. We have developed a suite that allows computational astrophysicists of all backgrounds to easily and efficiently build models of white dwarf stars that they can utilize for their own research purposes. By streamlining the process of modeling a white dwarf computationally, and by employing the power of modern physics, we can trim the process of white dwarf building from hours down to minutes. For the future of this project, this suite could push the boundaries of stellar astrophysics physics, allowing us to study kinds of white dwarfs that haven’t been observed in space, or to dissect more puzzling real-world white dwarfs with unexplained behaviors and characteristics.

The purpose of this project is to build a data collection system that can obtain pressure readings in a wind tunnel to determine the speed of the airflow. In this project, data is collected by a pressure sensor and then is interpreted by a microcontroller. This involved building the circuit and programming the microcontroller to receive data from the sensor. We then used an equation that relates the readings from the sensor to a pressure value. When this is complete, we will be able to obtain real time pressure readings from a wind tunnel, which can be used to interpret the impact objects in the wind tunnel have on the airflow. The next step of this project will be to calibrate the sensor with the wind tunnel and determine the baseline airflow profile of the wind tunnel.

Understanding the aerodynamics of systems is crucial in the design of vehicles and structures. Wind tunnels provide a controlled environment to analyze airflow around models that help inform the design process. Large scale wind tunnels are expensive and in this project, we are investigating whether we can observe similar behavior to large wind tunnels using a smaller scale version that can be constructed at significantly lower cost. In this poster we describe our design and present measurements of the airflow showing the effectiveness of design features such as a flow straightener, screen, and baffles to reduce turbulence. Construction of the wind tunnel also provides a platform for future research opportunities.

This research details the results of work done in Modules for Experiments in Stellar Astrophysics (MESA) on cataclysmic variables. Cataclysmic variables are binary systems of stars that orbit each other with a period of a few hours. In these systems, mass is transferred between one star and the other, often alternating between times where mass is transferred quickly, and other times where it is transferred slowly. Recent work has suggested that the transferred matter is rapidly processed from hydrogen and helium to carbon and oxygen, resulting in the long-term growth of the star that received the matter. Our model uses MESA to track the variable mass transfer at small time scales. We show that long-term growth is inhibited by periodic explosions known as classical novae that eject most of the matter that was transferred, casting doubt on the earlier results indicating efficient stellar growth.

Aim: To explore the use of various definitions for the exact moment a collapsing cloud of gas and dust becomes a star, often called the zero-age main sequence (ZAMS).Context: In stellar models, the definition of when a collapsing cloud of gas becomes a fully-fledged (hydrogen burning) star, can be characterized in many ways. To obtain data, we stop a computational star model when each of the various “definitions” is met, graph, and analyze to determine how well the data represents a newly matured star.Methods: This study uses MESA (Modules for Experiments in Stellar Astrophysics) to generate computational star models for 30 stars of initial masses between 0.126 solar mass and 100.0 solar mass. The stopping conditions explored involve the central hydrogen abundance, the ratio of power created by fusion to total power leaving the star, and, most notably, a quantity that compares the local luminosity gradient with the nuclear energy generation rate, which should balance for a star that is powered primarily by nuclear fusion.Results: We present Hertzsprung Russell diagrams depicting the isochrones of star models using the different stopping conditions. While the investigated stopping conditions typically generate similar star populations, some are able to catch stars slightly earlier in their evolution. We make a subjective argument for favoring a luminosity gradient vs. nuclear energy generation rate definition of the ZAMS.