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Toward a green circular economy – improving small scale renewable ammonia using absorbent-enhanced Haber-Bosch
No full textUniversity of Minnesota Ph.D. dissertation. March 2025. Major: Chemical Engineering. Advisors: Alon McCormick, Paul Dauenhauer. 1 computer file (PDF); xviii, 133 pages.With carbon emissions continuing to increase yearly including reaching record levels of 37.4 giga tons of CO2 in 2023, there is a global desire to reduce greenhouse gas emissions and mitigate its negative impact on our climate system. A major reason for the increase in CO2 emissions is our linear economic model – take, use and dispose. This model relies on the extraction and utilization of fossil fuels to drive almost every aspect of global economic activity, releasing large volumes of carbon emissions in the process. The availability of renewable resources like wind, hydro and solar provide much needed clean energy alternatives, however, they are intermittent in supply and are mostly abundant in uninhabited areas, making them difficult and expensive to store and transport to population centers. One solution is to store energy from these renewables as ammonia. Ammonia provides a cheaper medium for long-term energy storage compared to hydrogen which requires expensive compression. Ammonia can also be used as a fertilizer, feedstock for specialty chemicals, converted into hydrogen fuel or burned directly to produce energy for various applications, making it an ideal vehicle for a decarbonized and sustainable economy.Synthesizing carbon-free ammonia using renewables like air, water and renewable electricity on a small-scale (<100 tonnes per day), which is suited for the intermittent nature of renewables, is very expensive. One way of reducing this cost is by replacing the traditional ammonia separation by condensation with reactive absorption using metal halides like MgCl2. In this process, the incoming ammonia reacts with the salt particles to form amminated salt, and this complex salt breaks down upon heating to release the ammonia. Although this method of ammonia separation is more efficient, pure metal halides are unstable and show decreasing capacity with prolonged usage. Incorporating inert support like silica beads into the absorbent material helps to stabilize its capacity but the mechanism through which stability is achieved is unclear. Furthermore, the optimum operating conditions that will yield the most ammonia per time during a cyclic ammonia absorption and desorption process in a small ammonia plant is not known. In addition, because ammonia absorption is very exothermic, the salt particles heat up to high temperatures upon contacting ammonia. This inhibits further ammonia uptake and limits the ammonia capacity for these materials. Finding better thermally conductive support would improve heat transport in the absorbent bed.
By designing an experimental method for studying the supported metal halides - MgCl2, the mechanism for stabilizing ammonia absorbents using inert support was revealed: mass transport is aided by support providing enough surface for dispersed small salt crystals to form. Using this stable performing material, 40 wt.% MgCl2-SiO2, process optimization studies were performed to determine the process conditions that will yield the most ammonia per time during a cyclic ammonia absorption and desorption process. Using a sufficiently high regeneration temperature (~200 ⁰C) allowed for a small amount of sweep gas to be used for absorbent regeneration. Of note, the ammonia product exceeded 72 mol% purity in a mixture of N2 and H2. High ammonia capacities (about 154 mg NH3/g absorbent) were achieved within 33% or less time than was previously studied. Insights from the MgCl2-SiO2 system, enabled the design of a thermally conductive composite absorbent, MgCl2-Al. With a bed thermal conductivity (4.6 ± 0.1 W/m.K) up to an order of magnitude higher than MgCl2-SiO2, the MgCl2-Al material enabled heat to be conducted more efficiently throughout the absorbent bed during ammonia absorption and desorption; thus resulting in higher ammonia production yield.Onuoha, Chinomso. (2025). Toward a green circular economy – improving small scale renewable ammonia using absorbent-enhanced Haber-Bosch. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/273525
Minutes: Civil Service Consultative Committee: May 8, 2025
No full textIn these minutes: Welcome; Reports to the Senate; Office of Human Resources-Pay Plan Update and Vote; Chair-Elect Vote; Board of Regents Report Discussion; Loss of Pregnancy Rules Change UpdateUniversity of Minnesota: Civil Service Consultative Committee. (2025). Minutes: Civil Service Consultative Committee: May 8, 2025. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/273666
A case study: how organizational ethical culture is created, implemented, & sustained in an intercollegiate athletic department.
No full textUniversity of Minnesota Ph.D. dissertation. Spring 2025. Major: Kinesiology. Advisor: Lisa Kihl. 1 computer file (PDF); v, 181 pages.This study investigated the development of an organizational ethical culture within an NCAA Division I intercollegiate athletic department, drawing upon Valentine’s (2014) model of organizational ethics. Using a single case study approach, the research delved into how ethical culture is created and maintained in this unique context, contrasting it with traditional corporate organizations. Findings revealed that the athletic department’s ethical culture prioritizes alignment with the institution's holistic mission over revenue generation or competitive success. A familial environment emerged as a key factor, fostering intrinsic motivation among stakeholders and strengthening their commitment to ethical values. This research contributes a new conceptual model for ethical culture in intercollegiate athletics, highlighting the significance of strategic leadership and ethical values. While the findings are based on a single institution and warrant cautious generalization, they offer fresh insights for practitioners aiming to cultivate ethical cultures in their departments. The study underscores the need for further research in this area, addressing the unique challenges and opportunities within intercollegiate athletics and their implications for organizational ethics literature.Day Jr., Robert. (2025). A case study: how organizational ethical culture is created, implemented, & sustained in an intercollegiate athletic department.. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/275872
Design of high-efficiency accelerators for diverse AI workloads
No full textUniversity of Minnesota Ph.D. dissertation. March 2025. Major: Electrical Engineering. Advisor: Yu Cao. 1 computer file (PDF); x, 78 pages.Artificial intelligence (AI) has evolved from dense Deep Neural Networks (DNNs) toward a diverse set of models, such as sparse graph convolutional neural networks (GCNs), LLMs. To efficiently process these workloads AI accelerators are inevitable. But designing AI accelerators is challenging as these new models differ in model size, processing flow, memory access patterns, and data/model sparsity. This thesis discusses the key design requirements of AI accelerators, including reconfigurability, heterogeneity, and scalability, to efficiently accelerate AI models. Based on these findings, three works are proposed. A FPGA based dynamically reconfigurable GCN accelerator that efficiently handles the heterogeneous sparse and dense compute pattern in GCN. Different from deep neural networks (DNNs), GCNs are sparse, irregular, and unstructured, posing unique challenges to hardware acceleration with regular processing elements. To overcome these challenges, we propose an end-to-end hardware-software co-design to accelerate GCNs on resource-constrained FPGAs with the features including: (1) A custom dataflow that leverages symmetry along the diagonal of the adjacency matrix to accelerate feature aggregation for undirected graphs. (2) Unified compute cores for both aggregation and transformation phases, with full support to the symmetry-based dataflow. (3) Preprocessing of the graph in software to rearrange the edges and features to match the custom dataflow. The accelerator is implemented in Intel Stratix10 MX FPGA board with HBM2, and demonstrate 1.3×-110.5× improvement in end-to-end GCN latency operations as compared to the state-of the-art FPGA implementations, on the graph datasets of Cora, Pubmed, Citeseer and Reddit. To address the need for a heterogeneous accelerator to support the diverse set of AI workloads a new RISCV based reconfigurable heterogeneous accelerator, with the target to balance the computation needs and energy efficiency is proposed. Based on representative DNNs and GCNs, we propose two types of processing elements (PEs): (1) A Latch-based digital IMCs (LIMC) for regular and dense computation, and (2) A digital SIMD array (SIMD) with fine-grained control for irregular and sparse workloads. iv To integrate both types of PEs and dynamically manage the data flow, we design reconfigurable modules of scatter/gather and buffers, supporting different types of memory access and compute patterns. The new heterogeneous accelerator has been designed and taped out at 16nm. Based on 16nm design data, it achieves an 11× improvement in latency compared to baseline homogeneous accelerators, and up to 2.1× and 20× improvement in TOPS/mm2 and TOPS/W, respectively, as compared to state-of-the-art accelerators. With AI models evolving at a rapid pace and along with a huge amount of data volume, it is critical that AI accelerators also be easily scalable to meet the performance and data bandwidth requirements. Traditional computer vision tasks in autonomous machines and AR/VR rely on high-speed links, such as MIPI CSI-2, to transfer data from sensors to computing units.While these systems have struggled in the past to meet the growing demands on high bandwidth and low latency, today’s advanced packaging technologies that allow for multiple tiers of sensing and computing chiplets to be stacked together have the potential to support real-time processing of these tasks. In this work, we utilize advanced packaging technology, specifically 3D die stacking with high-density copper (Cu) pillars, to develop a 2-tier hardware-software co-design for an AI ViT accelerator. Ultimately, this 2-tier accelerator will be integrated with the sensing tier to process continuous data streams. Our 3D stacking approach, featuring face-to-face bonding with a 5µm pitch, offers two key advantages: (1) higher compute density than what is offered by 2D / 2.5D packaging and (2) higher connection density than conventional TSV-based stacking. Our synthesis results at 28nm demonstrate an 18x improvement in latency and a 127x reduction in energy consumption compared to conventional 2D designs and an 11x improvement in latency compared to similar 3D architecture.Raveendran Nair, Gopikrishnan. (2025). Design of high-efficiency accelerators for diverse AI workloads. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/273527
Data for Multi-objective OLED Optimization Manuscript
No full textThis dataset contains .csv files for the data contained in Figures 2-3, 5, 7-9 in the manuscript. See readme.txt for more detailed information.This dataset contains all the data required to recreate the figures in the manuscript entitled "Multi-objective OLED Optimization". This dataset contains both experimental and simulated data for green, bottom-emitting organic light-emitting devices (OLEDs). Its value is in elucidating broadly applicable design trends and optimized designs for multiple performance metrics.Microsoft CorporationRamamurthy, Maya; Pakhomenko, Evgeny; Keil, John; He, Siliang; Kapur, Abhinav; Hershey, Kyle W; Zheng, Ying; Holmes, Russell J; Ferry, Vivian E. (2025). Data for Multi-objective OLED Optimization Manuscript. Retrieved from the Data Repository for the University of Minnesota (DRUM), https://doi.org/10.13020/xak0-gx77
Associations Between Expressed Parent Affect and Child Behavior Difficulties
No full textThis research was supported by the Undergraduate Research Opportunities Program (UROP).Shankar, Shreya; Palmer, Alyssa; Berry, Daniel. (2025). Associations Between Expressed Parent Affect and Child Behavior Difficulties. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/276410
Economic contribution of Alomere Health 2024
No full textExtension's research is informed by the programs and partnerships we have with communities across the state. Learn more at extension.umn.edu
Minutes: Benefits Advisory Committee: April 24, 2025
No full textIn these minutes: Welcome and Comments from the Chair; Employee Benefits Update; Personify Health Presentation; Employee Survey Results for Personify HealthUniversity of Minnesota. Benefits Advisory Committee. (2025). Minutes: Benefits Advisory Committee: April 24, 2025. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/273671
Commission on Equity, Race, & Ethnicity: History
No full textThis history was printed from the Commission on Equity, Race, and Ethnicity website on August 26, 2025.University of Minnesota Duluth. Commission on Equity, Race, and Ethnicity. (2025). Commission on Equity, Race, & Ethnicity: History. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/276321
Minutes: Commission QT, March 17, 2025
No full textUniversity of Minnesota Duluth. Commission QT. (2025). Minutes: Commission QT, March 17, 2025. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/276397