Browsing by Subject "Engineering"

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Characterization of Lightweight, Low-Force Cable and Hydraulic Transmission Systems
(2022-08) Kivi, Andrew
In the field of rehabilitation robotics and wearable exoskeletons, a common challenge forsystem designers is how to transmit force from the actuators to the joints. In small-scale applications, for the working range of 50-500 N, cables and hydraulics are the two most common ways to transmit force. This study characterized wire rope, braided synthetic line, Bowden cable, and hydraulic transmission types based on their size, weight, efficiency, and controllability. Analytical and experimental methods were used to evaluate individual aspects of each transmission. Analysis was performed to compare the transmission types. The rate at which cables increase in size and weight is approximately linearly with rated load; however, cable construction had the largest influence on the rate of increase. It was observed that cable stiffness can be fit to a 1/L model in the approximate range of 20 to 50 cm, but not for much longer lengths. Hydraulic stiffness was modeled, and it was shown for small diameter actuators the stiffness is comparable to the cables studied. Cable efficiency was studied using the capstan equation and found to be Coulomb friction dependent decreasing as wrap angle or coefficient of friction increased. Bowden cable efficiency is also friction dependent, however Bowden cables do not follow the capstan equation. Over-constrained Bowden cable paths led to more surface contact and decreased efficiency. Hydraulic transmission efficiency is dependent on hose diameter and flowrate. Optimal designs operate at high working pressures and low flowrates. It was shown in a case study that the optimal transmission type is often application dependent.
The community college baccalaureate and Iron Range Engineering: limiting rural brain drain in Northeastern Minnesota by offering a hands-on baccalaureate degree on a community college campus.
(2011-05) Janezich, Trent Patrick
Two educational organizations have collaborated on a nationally recognized, innovative, project-centered engineering curriculum for the third and fourth year of a baccalaureate degree in which hands-on experiences and industry-sponsored projects are the fundamental component of the degree. The Iron Range Engineering (IRE) program curriculum is of a type that has never been attempted in the state of Minnesota. This program creates a career pathway for engineering students in rural northeastern Minnesota in the hopes to help stop rural brain drain in an area of Minnesota losing its young human capital in alarming numbers. IRE also provides access to a baccalaureate degree in engineering on a community college campus of the Northeast (Minnesota) Higher Education District by partnering with Minnesota State University, Mankato. The heart of this curricular innovation is a shift from a conventional classroom learning environment to industry-style learning environments where baccalaureate-level students will work on real-world projects alongside practicing engineers. These projects are not merely internships or field trips. They are in fact the very content of the curriculum, experienced by students in a competency-based, experiential approach never before used for engineering education in Minnesota. This descriptive case study allows the first generation cohort of students to describe in their own words the Iron Range Engineering program. Ten findings that describe the Iron Range Engineering program emerged. Implications for community college baccalaureate delivery are discussed, and future research possibilities are presented.
Design, Development, and Evaluation of Wearable Length Fastening Devices for Use with Twisted Coiled Actuators
(2023-04) Dorn, Timothy
Artificial muscles and compliant, large stroke linear actuators have enabled new classes of wearable robotics. However, these actuators are inefficient, needing constant power to maintain force and displacement, decreasing their utility in wearable systems. Variable length latching mechanisms alleviate this problem, matching actuator displacement, and holding force and displacement constant when the actuator is powered off. However, most existing latching designs are either not wearable, or must be disengaged manually, limiting their robotic applications. In this research, three wearable and remotely releasable latching mechanisms were designed for use in wearable robotic systems: a stepper motor with a belt and pulley; a linear ratchet; and a cam cleat. The designs were manufactured and tested, with all three designs maintaining force and displacement values up to 15N of cable tension and releasable up to 5N of cable tension. These results demonstrate the viability of integrating latches into soft wearable robotic systems.
Developing methods to understand and engineer protease cleavage specificity
(2016-09) Lane, Michael
Proteases are ubiquitous enzymes that comprise nearly 2% of all human genes. These robust enzymes are attractive potential therapeutics due to their catalytic turnover and capability for exquisite specificity. While most existing drugs require a stoichiometric ratio to function, therapeutic proteases could clear their targets much more efficiently. Unfortunately, existing technologies are inadequate for understanding and engineering therapeutic proteolytic specificities. My thesis work has focused on building the groundwork to enable these technologies to thrive. For the goal of engineering a new protease, it is currently necessary to identify prototype proteases for engineering efforts that have specificities similar to the desired target substrate. Current technologies are unable to characterize proteases adequately for this goal. Accordingly, I invested in developing a method for the accurate characterization of protease cleavage specificity. Our unique combination of mRNA display technology, Next-Generation Sequencing, and mass spectrometry enables the sampling of all possible permutations of octamer substrates and the identification of millions of cleavage sites. The throughput of our approach is orders of magnitude greater than the current state-of-the-art methods. The resulting high-resolution specificity maps can be applied to identify promising protease prototypes, predict human cross-reactivity, or lead to a better understanding of this critical component of natural physiology. In the work presented here, I applied my new specificity-screening method to assess the specificities of the proteases factor Xa, ADAM17, and streptopain. The resulting cleavage preference maps confirmed known specificities, and revealed new insight into the broad preferences of both narrow- and broad-specificity proteases. In particular, disfavored amino acids were illuminated better than ever before. The next focus of my work was to engineer multiple-subsite novel protease specificity. I chose streptopain as the prototype for my efforts to neutralize the superantigen exotoxin SpeA. I identified a target loop of SpeA wherein cleavage would result in inactive fragments. Further, I confirmed that streptopain can be successfully presented as an mRNA displayed fusion. In summary, my thesis work established crucial methodologies for applying mRNA display technology to enable the understanding and ultimately engineering the specificity of therapeutic proteases.
Development Of A Comprehensive Backcalculation Procedure For Rigid Pavement Design Parameters Using Slab-Edge Deflection Basins
(2016-06) Paitich, Samuel
Backcalculation of structural parameters for rigid pavements is commonly conducted with falling weight deflectometer (FWD) deflection basins measured at the center of slabs. Although a number of established techniques exist to backcalculate pavement parameters for the slab-center location, a reliable technique to backcalculate such parameters at the neighboring slab-edge location does not exist. The slab-edge location is critical to the design and management of rigid, concrete pavements because high stress levels and early signs of degradation originate at the slab edge. An edge backcalculation procedure accounting for the load transfer efficiency (LTE) of inter-slab joints is developed in this study. The proposed procedure is based on finite element modeling and dimensional analysis. Testing and validation of the edge backcalculation procedure is performed using FWD basins measured at the slab-edge location of in-situ pavements, along with measured LTEs, via the Long Term Pavement Performance (LTPP) program. Some prospective applications of the new procedure, in conjunction with the LTPP database, are presented. It is shown that the new edge backcalculation procedure is robust and satisfactory, particularly for pavements in good structural condition.
The effect of radial convection on cell proliferation Iin bone tissue engineering
(2009-04) Shao, Weiru
Large bone defects are frequently encountered during surgeries. Traditional methods of repair are limited by bone graft availability and increased surgical morbidity. Tissue engineered bone tissue has many clinical advantages. However, its current technology is limited by implant size and lacks of immediate nutritional perfusion once the tissue is implanted. Objective: To sustain cell growth and proliferation in a three-dimensional scaffold unit with radial convective flow. Material and Methods: Fetal rat calvarial cells were harvested and loaded into 1x1 cm hydroxyapatite cylinders. Microperforated hollow fibers were placed at the center of the cylinders to generate radial convective flow with oxygenated cell culture medium under hydraulic pressure. Live cell densities within the blocks were determined after 8 days of convection. Results: Radial convection sustained cell growth and proliferation better than simple diffusion at all three zones of the cylinders: center, outer, and rim. Conclusion: Radial convective flow is capable of supporting cellular function and proliferation in small scaffold units. The design of the radial convection units and their system parameters are validated by this study. The results are very useful to devise future tissue engineering studies involving radial convective flow.
Engineering problem finding in high school students.
(2009-06) Franske, Benjamin James
The purpose of this study was to explore the engineering problem finding ability of high school students at three high schools in Minnesota. Students at each of the three schools had differing backgrounds including pre-engineering coursework, traditional technology education coursework and advanced science coursework. Students were asked to find problems in two different engineering scenarios which were presented to them on a paper and pencil instrument. Responses were scored by a panel of judges based on measures of creativity (flexibility, fluency, originality and elaborateness) and analyzed based on demographic data including gender, prior coursework and school. In addition student responses were categorized and evaluated qualitatively based on school and gender of respondent. Quantitative results indicate that the most consistent predictor of creativity in engineering problem finding scenarios was the number of advanced science classes. Specific measures of creativity included other significant predictors but advanced science coursework was the most consistent across all measures and scenarios. The qualitative results showed striking differences in the responses from students at different schools. Students from schools with a pre-engineering and advanced science emphasis found similar categories of problems and had a similar view of the purview of engineers while students with a technology education background focused on a rather different set of problems and had a much narrower view of engineering. Results show clear differences in the types of problems found by students at these three high schools as well as their understanding of the scope of engineering problems. Educators need to become more aware of the importance of problem finding in engineering and better encourage the development of problem finding skills among their students. Specifically, technology education teachers may need supplemental professional development related to the scope of engineering and engineering problem finding as well as how these concepts might be infused into their curriculum and encouraged among their students.
Epistemic Practices in Collaborative Contexts: Examining how Middle School Students Participate during Small Group Engineering Design Activities
(2023-05) Sivaraj, Ramya
Small group engineering activities offer opportunities to examine collaborative interactions and discourse as students make sense of engineering problems and design solutions. This study examined epistemic practices in small group learning experiences focused on engineering design problems in a middle school science class. Student discourse was analyzed to identify epistemic practices used by students. Findings indicate that students engaged in sixteen epistemic practices of engineering (EPEs) largely independent of facilitation or scaffolding by their teacher. The progression of epistemic practices reflected how students were able to participate effectively in EPEs toward a design solution for a laser security system. Students first situated their problem in context followed by envisioning solutions. Subsequently, they worked together to develop a group design model, constructed a prototype, and iteratively tested and refined their design until the prototype was functional. Student innovation was observed both during the brainstorming of contextual factors and in the novel use of materials to complete the group design prototype. Students applied mathematics and science knowledge, utilizing the laws of light reflection, both in discourse and interactions during model design and prototype development. Student collaborative participation and epistemic discourse contributed to design solutions. Students iteratively refined their prototype by working together to implement design changes that led to guiding the laser beam and positioning mirrors toward a target. Additional evidence of collaborative discourse included collective ownership through student revoicings and reification of each other’s ideas and suggestions. Collective ownership facilitated student collaboration and design decisions toward the setup of a functional group prototype. The findings highlight implications related to the structure and design of small group collaborative K-12 engineering learning experiences. These implications include the need to further encourage and examine collaborative epistemic participation in small group learning. Implications also extend to curricular design of engineering activities that consider engagement in EPEs, including design innovations and application of mathematics and science knowledge, with a focus on student-centered pedagogy.
Factors influencing African American high school students in career decision self-efficacy and engineering related goal intentions.
(2009-10) Austin, Chandra Yvette
A current challenge in the United States is to increase African American pursuit of engineering careers. Minority students generally tend to be under-represented in such careers, as indicated by the National Academy of Engineering, in The Engineer of 2020-Visions of Engineering in the New Century. This study explores the career decision self-efficacy (Lent, Brown & Hackett, 1993) and Engineering related goal intentions of African American high school students. There are a variety of reasons explaining the lack of choice of engineering as a career, and these were investigated. This study assessed the effect of specific influences (ethnic identity, demographic factors, ability, school factors, Math/Science confidence, Math/Science self-efficacy, Math/Science interest, and family support) on career decision self-efficacy and engineering related goal-intentions. Data from a survey of 396 African American students' grades 9-12, low-middle income level, in a southeastern school were used in the study. Results show that career decision self-efficacy among students studied is influenced by: Math/science confidence, ethnic identity, family relations, school factors, and socioeconomic status. Factors influencing engineering related goal intentions were very similar but each variable did not contribute the same amount of variance. Results also show that gender was not significant in either dependent variable. Other implications and recommendations relating to the variables are presented.
Improved Base Editing Technologies With Novel Editors and Assays
(2018-10) St. Martin, Amber
Genome engineering is a rapidly evolving area of study. One driver of the breakneck speed with which the field is moving forward is the application of CRISPR/Cas9. Since its introduction in 2013, CRISPR/Cas9 has completely changed the ease and utility of genome engineering and has revolutionized the field. The use of CRISPR/Cas9 to directly edit genes, increase or decrease gene expression, or even image genomic loci is widely accepted and extensively used in models ranging from bacteria to mammals. The recent development of second-generation CRISPR editing tools has opened even more doors into how the human genome can be manipulated. Past methods to introduce a single-base substitution into genomes involved creating a double-strand break and taking advantage of the cellular repair pathway homologous recombination to incorporate a donor plasmid into the genomic sequence. These methods are inefficient and can result in introduction of the donor template into numerous unrelated loci throughout the genome, unwanted insertions or deletions, or chromosomal translocations. Base editing unlocks a method to introduce single-base substitutions without the need for a donor template or the creation of a double-strand break. By fusing rat APOBEC1, a natural cytosine deaminase, to Cas9 nickase and uracil DNA glycosylase inhibitor, the Liu lab was the first to create an RNA-guided base editor that can change target cytosines to thymines. In just a year and a half, significant improvements have been made on this front, including making the original base editor more efficient and specific and even introducing editors with the power to mutate adenosines to guanosines. Despite the advancements constantly being made to this technology, there is still room for improvement. The current base editors such as BE3 can edit unintended cytosines in the target sequence at high rates. In addition, the combination of the nickase activity of Cas9 and the abasic site created after deamination of the target cytosine can create a pseudo double-strand break resulting in creation of unwanted insertions or deletions. Finally, targeting at endogenous loci continues to hover between 30% and 80%, depending on the method used and model genome being targeted. Targeting rates could benefit from growth, especially as this technology is being considered for therapeutic applications. A bottleneck in the process of developing new and improved base editing technology is the time and effort that is required to quantify editing efficiencies. Most studies use next-generation sequencing to quantify editing rates. The preparation of samples and quality control required can take up to six weeks. If using a core at a larger university or research institution there is additional time spent waiting in a queue to use a sequencing instrument. The field is in need of a rapid method to quantify base editing in real time that is transferable to multiple cellular systems. Here I report two bicistronic, fluorescence-based systems for the quantification of base editing activity. By changing a 5’-TT-3’ dinucleotide motif to a 5’-TC-3’ dinucleotide motif in eGFP or mCherry, I simultaneously ablate fluorescence and create an APOBEC-preferred mutational hotspot. When the cytosine is reverted back to a thymine, fluorescence is restored. This tight off-to-on system allows for real-time quantification of base editing activity through fluorescence microscopy or flow-cytometry. After creating a novel base editing reporter system, I hypothesized that I could use the newly designed assay to create more efficient and specific base editors. Using members of the human APOBEC3 family of enzymes, I created a suite of novel base editors. These base editors have advantages over rat APOBEC1-based editors in that the structure of many APOBEC3s are known, allowing for easier structure-guided evolution to improve their editing activity. As a proof of concept, I used this knowledge to evolve APOBEC3H haplotype II into a more efficient base editor by making only a few amino acid substitution mutations. In addition, we were able to create base editors using APOBEC3A and the catalytic domain of APOBEC3B that surpass BE3 in editing efficiency. Taken together, these data contribute positively to the genome engineering field and open new doors for continuing development of this technology.
Integration of Engineering education by high school teachers to meet standards in the physics classroom
(2013-08) Kersten, Jennifer Anna
In recent years there has been increasing interest in engineering education at the K-12 level, which has resulted in states adopting engineering standards as a part of their academic science standards. From a national perspective, the basis for research into engineering education at the K-12 level is the belief that it is of benefit to student learning, including to "improve student learning and achievement in science and mathematics; increase awareness of engineering and the work of engineers; boost youth interest in pursuing engineering as a career; and increase the technological literacy of all students" (National Research Council, 2009a, p. 1). The above has led to a need to understand how teachers are currently implementing engineering education in their classrooms. High school physics teachers have a history of implementing engineering design projects in their classrooms, thus providing an appropriate setting to look for evidence of quality engineering education at the high school level. Understanding the characteristics of quality engineering integration can inform curricular and professional development efforts for teachers asked to implement engineering in their classrooms. Thus, the question that guided this study is: How, and to what extent, do physics teachers represent quality engineering in a physics unit focused on engineering? A case study research design was implemented for this project. Three high school physics teachers were participants in this study focused on the integration of engineering education into the physics classroom. The data collected included observations, interviews, and classroom documents that were analyzed using the Framework for Quality K-12 Engineering Education (Moore, Glancy et al., 2013). The results provided information about the areas of the K-12 engineering framework addressed during these engineering design projects, and detailed the quality of these lesson components. The results indicate that all of the design projects contained components of the indicators central to engineering education, although with varied degrees of success. In addition, each design project contained aspects important to the development of students' understanding of engineering and that promote important professional skills used by engineers. The implications of this work are discussed at the teacher, school, professional development, and policy levels.
Lessons for High School Students: 2008 Implementation and Evaluation Report
(University of Minnesota Center for Transportation Studies, 2008-12) Glick, David A.
The Intelligent Transportation Systems (ITS) Institute at the University of Minnesota is developing materials for high school students in an effort to increase their awareness of transportation-related issues and careers. Five lesson plans were developed in early July 2008 and piloted during three of the four weeks of Exploring Careers in Engineering & Physical Science (ECEPS), a summer camp experience for high school students that is a program of the Institute of Technology Center for Educational Programs (ITCEP) at the University of Minnesota. Lesson plans were continuously modified during the summer camps based on feedback from surveys that were administered to students. The modifications were needed to help improve the lesson plans for future high school classroom use. In addition, the lesson plans were piloted at Patrick Henry High School in Minneapolis, MN in October 2008. The lesson plans will be piloted at two additional high schools in the next several months; Anoka-Hennepin Secondary School in Anoka, MN and Maplewood High School in Maplewood, MN. The lesson plans were also presented at the Minnesota Science and Math Teachers Association in October 2008 to gain interest from teachers. Feedback from survey results and discussions with teachers, will allow for the implementation of new curriculum enhancements and designs for future transportation lessons.
Probabilistic Knowledge-guided Machine Learning in Engineering and Geoscience Systems
(2024-06) Sharma, Somya
Machine learning (ML) models have achieved significant success in commercial applications and have driven advancements in scientific discovery across many scientific disciplines. ML modeling has been essential in tackling complex scientific problems, often enhancing our understanding of previously poorly understood processes. These models have been developed to improve computational efficiency in scenarios where traditional process-based or mechanistic models provided only simplified approximations of physical processes. Despite their success, even state-of-the-art ML models can produce physically inconsistent predictions and have limited generalization capabilities. Additionally, the black-box nature of ML models means that researchers and stakeholders often lack insight into their reliability. This thesis proposes the development of novel Probabilistic Knowledge-Guided Machine Learning (P-KGML) models to address these concerns. P-KGML models integrate domain knowledge and probabilistic reasoning to improve the explainability, generalization, and physical consistency of ML outputs. These models are particularly valuable in engineering and geoscience systems, where understanding uncertainty and ensuring adherence to physical laws are crucial.
Using citation analysis methods to assess the influence of STEM education evaluation
(2008-05) Greenseid, Lija Ozols
This study explores the validity of using citation analysis methods as a way of assessing the influence of program evaluations conducted within the areas of science, technology, engineering, and mathematics (STEM). Interest in the broad influence of evaluations has caught the attention of evaluation theorists, practitioners, and funders recently. However, methods for measuring the influence of evaluations have yet to be developed and validated. Citation analysis is widely used within scientific research communities to measure the relative influence of scientific research and/or specific scientists. This study explores the applicability of citation analysis for understanding the broad impact of STEM education program evaluations. Nine assumptions regarding the validity of using citation analysis methods to assess STEM education evaluation product influence are examined using data from four sources: (1) citation analysis data, (2) the opinions of an expert panel, (3) data from a survey of primary investigators and evaluators from local projects connected with four national program evaluations, and (4) a review of relevant literatures. The data collected for the validation study suggest that citation analysis methods provide data to help understand, to a limited extent, the influence of large-scale program evaluations on the fields of STEM education and evaluation. In particular, citation data can be used to understand and compare patterns of influence of multi-site STEM program evaluations. Citations, however, are only one among many possible measures of one limited type of influence arising from the dissemination of evaluation products. Additionally, citation data do not appear to be useful for precisely quantifying the actual level of influence of any one evaluation. Moreover, the examination of the content of citations is critical. Without understanding the content of the citations, judgments cannot be made about whether citations are actually measuring influence. Consequently, it is important to stress that citations are only one measure of one possible influence arising from an evaluation and are limited and should be interpreted as such.
Using household travel surveys to adjust ITE trip generation rates
(Journal of Transport and Land Use, 2015) Currans, Kristina M.; Clifton, Kelly J.
The Institute of Transportation Engineers (ITE) Trip Generation Handbook has become the predominant method for estimating vehicle trips generated by development. The handbook is often criticized for its inability to account for multimodal behavior in urban contexts, often overestimating vehicle traffic. The purpose of this research is to develop and test a ready-to-use method for adjusting the ITE handbook vehicle trip generation estimates for urban context. This method was created using household travel surveys from Oregon, Washington, and Maryland, as well as nationally available built environment data. Three adjustments were estimated for eight general land-use categories, including a “pooled” category considering all travel survey data. The performance of three adjustments were tested using 195 establishment-level vehicle trip generation datasets compiled from three independent sources. Using this data, the performances of four land-use categories were tested. The overall findings suggest that the simplest of the three adjustments developed provided similar results to the more complex adjustment methods. Moreover, adjustments applied using the “pooled” land-uses category also provided similar results to the more detailed segmentation of travel survey data. Both of these findings punctuate the need for a simple, urban adjustment for trip generation estimates.

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