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Fluid-structure interaction of steady and pulsating flow through a collapsible thin-walled vessel
Get PDFAn experimental study has been conducted to investigate complex fluid-structure interactions in collapsible tubes under steady and pulsatile flow conditions, which holds significant implications for many physiological fluid transport phenomena. Quantitative analysis of structural deformation and flow field analysis were conducted utilizing Particle Image Velocimetry (PIV) and optical image analysis. The results suggest that the tube wall deformation followed Shapiro?s tube law under static and low-Re steady flow conditions. An increase in flow magnitude triggered self-excited oscillation under a critical range of negative transmural pressure. PIV results revealed periodic asymmetric jet downstream alongside velocity fluctuations during self-excited oscillation. Pulsatile flow induced cyclic symmetrical buckling under positive and neutral transmural pressures, while created traveling wave patterns under negative transmural pressures. Under highly negative transmural pressures, tube collapsed during diastole, limiting the mean flow rate. Brief self-excited oscillation was observed under such conditions, amplifying the peak flow rate within a pulsatile cycle
Experimental investigation of novel designs for aerodynamic flow control over airfoils
Get PDFIn this study, an experimental investigation was performed to characterize and validate three novel flow control strategies for unsteady aerodynamics. These three strategies are based on active and passive flow control designs. The two active control strategies make use of smart material alloy?s (SMA) located on the leading and trailing edge of a Boeing-Vertol VR-12 airfoil used in rotorcraft wings. The SMA used were macro fiber composites (MFC) a piezo-electric actuator. These actuators were located at the 25% and 85% of the chord length. Two different implementation strategies are used: one as an active morphing of the leading and trailing edge, second as acoustic resonators on the leading edge. The third strategy was of a passive flow control structure located on the pressure side of the leading edge of a NACA 0012 airfoil. This strategy makes use a microcavity to mitigate the transient separation and dynamic stall. In addition to the three novel strategies, traditional approaches such as drooping of the leading and trailing edge were studies. All systems were tested in both a static condition where the airfoil is held stationary as a freestream velocity is applied to the airfoil. As well as testing with a dynamic motion of the airfoil simulating a sinusoidal pitching motion. All of these tests were performed in the open loop wind tunnel located in the advanced flow diagnostics lab. The details of the wings design, manufacturing, actuation, programing, control, and test implementation is reported herein. The flow fields were measured through use of 2-D particle image velocimetry (PIV) an optical diagnostic flow methodology used for characterization and validation of the designs. To capture more detail of the unsteady and unpredictable nature of the flow, time resolved 2-D PIV, is implemented to provide full details of the flow while each strategy undergoes multiple pitching cycles. All three flow control strategies showed positive improvements to the airfoil performance. The active morphing provided the largest performance boost as the flow remained attached throughout the pitching experimentation. Showcasing the improvement that active morphing has over traditional methods of droop. The acoustic resonance was a close follow-up showing improvement in both pitching and static conditions, however for the case of pitching the system was inconsistent. This has been attributed to the need to adjust the frequency generated while the angle of attack changes. Lastly the passive cavity structure showed limited improvement during light dynamic stall, improving the flow when compared to the baseline. However, the flow conditions needed to concisely prove the control strategy were not possible with the current equipment
Computational Methods for Bulk and Single-cell Chromatin Interaction Data
Get PDFChromatin interactions occur when the physical regions of chromatin in close proximity interact with each other inside the nucleus. Analyzing chromatin interactions plays a crucial role in deciphering the spatial organization of the genome. Identifying the significant interactions and their functionalities reveals great insights on gene expressions, gene regulations and genetic diseases such as cancer. In addition, single cell chromatin interaction data is important to understand the chromatin structure changes, diversity among individual cells, and the genomics differences between different cell types. In recent years, Hi-C, chromosome conformation capture with high throughput sequencing, has gained widespread popularity for its ability to map genome-wide chromatin interactions in a single experiment and it is capable of extracting both single cell and bulk chromatin interaction data.
With the evolution of experimental methods like Hi-C, computational tools are essential to efficiently and accurately process the vast amount of genomic data. Since the experiment costs are notably higher, optimized computational tools and methods are needed to extract most possible information from the data. Moreover, processing single cell Hi-C data imposes number of challenges due to its sparseness and limited interaction counts. So the development of computational methods and tools to process data from both single cell Hi-C and bulk Hi-C technologies are focused in this work and those are proven to be enhancing the efficiency and accuracy of Hi-C data processing pipelines.
In this dissertation, each chapter consists of a single individual method or a tool to enhance chromatin interaction processing pipelines and the final chapter focuses on the interplay between epigenetic data and chromatin interactions data. The studies that are focused on building computational methods include increasing data read accuracy for bulk Hi-C, identifying statistically significant interactions at single cell Hi-C data, and imputation of single cell Hi-C data to improve quality and quantity of raw reads. It is anticipated that the utilization of the tools and methods outlined in these studies will significantly enhance the workflows of future research on chromatin organization and its correlation with cellular functions and genetic diseases
Sexual Harassment and Employee Identification in Radio Broadcasting
Get PDFSexual harassment is often vaguely defined in policy and the purpose of this study was to learn if employees perceive sexual harassment in vague or specific terms. Exploring radio broadcasting employees was a new area of exploration for the multiple ways employees may identify with their employer: professional, organizational, and group identification (Lammers, Atouba, & Carlson, 2013).
For this study I primarily drew on interviews with 17 radio broadcasting employees about sexual harassment definitions and employee identification (profession, organization, and group). A survey instrument was used to collect demographic data and to collect baseline data for identification.
Results show that interviewees define sexual harassment, and the communicative behaviors that could be perceived as harassing, in vague or non-specific terms, like policy, as well as in specific terms. Interviewees also conflate terms like bullying or discrimination, with sexual harassment. Radio broadcasting employees in this study identified with their work in multiple ways. Although some identified most strongly with the profession, organization, or group, the majority identified with a combination, all, or none. The way employees view sexual harassment with their primary identification appears to be dependent on how they see reports of sexual harassment treated
Retrofitting Architectural Environments in Response to an Evolving Workplace
Get PDFThe typology of this thesis is centered around Architectural Environments within
commercial office buildings. The theoretical premise is based on the statement
that people are less productive when their work environment is cold, artificially
lit, and has limits to pattern and nature. This premise brings up the challenges
that the workforce has and will continue to have since the Covid-19 pandemic.
How can architects design environments (external, internal, intimate, etc)
with the opportunity to positively impact the productivity and marketability
of people, investors, and their work places. Can Architectural Environments
have a direct positive impact on productivity? How can we as designers
retrofit vacant and under-utilized commercial office buildings into clever,
thoughtful, and pattern-driven architectural environments that will not only
benefit our economy?s new style of remote work, but also provide employees
and communities with useful spaces that will set them up for their optimal form
of work/life productivity? To aid in solving these challenges, a book of design
patterns that reflect results in productivity and marketability will be produced.
The research strategies used in this thesis are historical research, qualitative
data research, and other combined strategies
Ranking Risk Factors in Financial Losses From Railroad Incidents: A Machine Learning Approach
Get PDFRaj Bridgelall is the program director for the Upper Great Plains Transportation Institute (UGPTI) Center for Surface Mobility Applications & Real-time Simulation environments (SMARTSeSM).The reported financial losses from railroad accidents since 2009 have been more than US$4.11?billion dollars. This considerable loss is a major concern for the industry, society, and the government. Therefore, identifying and ranking the factors that contribute to financial losses from railroad accidents would inform strategies to minimize them. To achieve that goal, this paper evaluates and compares the results of applying different non-parametric statistical and regression methods to 15?years of railroad Class I freight train accident data. The models compared are random forest, k-nearest neighbors, support vector machines, stochastic gradient boosting, extreme gradient boosting, and stepwise linear regression. The results indicate that these methods are all suitable for analyzing non-linear and heterogeneous railroad incident data. However, the extreme gradient boosting method provided the best performance. Therefore, the analysis used that model to identify and rank factors that contribute to financial losses, based on the gain percentage of the prediction accuracy. The number of derailed freight cars and the absence of territory signalization dominated as contributing factors in more than 57% and 20% of the accidents, respectively. Partial-dependence plots further explore the complex non-linear dependencies of each factor to better visualize and interpret the results.The authors express their deep gratitude to the following funding agencies? support: North Dakota State University and the Mountain-Plains Consortium (MPC), a University Transportation Center funded by the U.S. Department of Transportation under grant number DTRT13-G-UTC38.https://www.ugpti.org/about/staff/viewbio.php?id=7
Disconnect to Reconnect: Using Architecture and Master Planning to Aid in Personal Connection With Nature
Get PDFTechnology is rooted in our society from a very young age, everywhere you look a child has some electronic device in their hands, impacting their lives. This is not necessarily a good thing for development and presents an opportunity for improvement. Architecture is a possible way to address this problem through the use of programming and construction of buildings to build a connection with oneself and disconnect from technology. By looking at similar buildings and researching new ideas this can be investigated. The Wellness Retreat proposes a way to disconnect from technology and reconnect with yourself, providing spaces for all types of people from all walks of life. After a stay at the Wellness Retreat you will leave with a sense of self and less reliance on technology in our daily lives
Bioclimatic Architecture: Incorporating Sustainable Design Methods in Cold Climates
Get PDFSustainable practices have been a topic of interest for decades
within the design community. Architects and engineers alike are keen
on the use of alternative energy sources such as wind and solar, but
only recently have they shifted focus to building materials and methods
as a potential solution for more environmentally conscious design. Our
material selections and where they are sourced impacts our carbon
footprint in ways we are just beginning to understand. One such
material is the use of mass timber or cross laminated timber (CLT).
Introduced in Europe, mass timber construction has slowly grown in
popularity internationally. After years of implementation overseas, CLT
has finally made its appearance in the U.S. and has now even been
incentivized in cities such as Portland and Seattle to meet
sustainability requirements both locally, and at a state level.
Unfortunately these recent innovations in sustainable design are slow
to be implemented inland in areas such as the Midwest.
This thesis explores the use of CLT and other sustainable materials and
strategies in a Midwestern context. The intent of this thesis is to educate,
inform, and inspire people to invest in our environment and design for
the future by making sustainable building decisions in cold climates. To
do this, I developed a Sustainable Design Learning Center in Duluth
MN that uses design methods such as green building certifications
like LEED and WELL, the use of CLT, daylighting and other materials to
educate people on how we can build more intelligently for the future
of our planet
In Touch with Prairie Living, June 2023
Get PDFJune 2023 column for North Dakota and South Dakota newspapers
Remembering and Rebuilding the Broken
Get PDFCities throughout time have grown, thrived, persisted, and prospered. Equivalently, time and time again, cities have been seized, destroyed, and flattened to an unimaginable state.
Yet they rise again. Why? Because a city is more than buildings, and more than all the lives that have passed there. A city has a beating heart and each has been sculpted from its own history and built by its own people. That is why cities rebuild, because there is something there that humans are drawn towards, and history has shown it is not the built environment.
On February 24th, 2022, Putin?s army invaded Ukraine, a peaceful and sovereign country.
That decision altered Ukraine?s history forever, and the beautiful country will never be the same.
Someday, hopefully soon, Ukraine will also find itself facing the decision of how to rebuild. Through this thesis I hope to find the answer to the question:
What is the most appropriate way to respond to the destruction of the war in
Kharkiv, UA while remaining sensitive to its history and culture