Experimental comparison of cycle modifications and ejector control methods using variable geometry and CO2 pump in a multi-evaporator transcritical CO2 refrigeration system

To reduce the direct global warming impact of refrigerants in HVAC&R applications, low-global warming potential (GWP) refrigerants, including natural refrigerants, have been extensively investigated as alternatives to hydrofluorocarbon (HFC) refrigerants. Among the natural refrigerants, Carbon Dioxide (CO2) offers several advantages, such as excellent transport and thermo-physical properties, being neither toxic nor flammable, and having a low price and high availability around the world. However, the high critical pressure and low critical temperature of CO2 often lead to transcritical operation, resulting in lower efficiency due to the additional compressor power necessary to achieve transcritical operation relative to subcritical HFC cycles. Therefore, a number of cycle modifications are used to enhance the coefficient of performance (COP) of transcritical CO2 cycles to meet or surpass those of HFC cycles. This paper provides a systematic experimental investigation of four such cycle architectures by employing the same multi-stage, two-evaporator CO2 refrigeration cycle test stand, 3 of these configurations in transcritical and 1 in subcritical conditions. The four cycles architectures included intercooling, open economization, an internal heat exchanger and two different ejector control approaches. Specifically, a variable-diameter motive nozzle and a variable-speed liquid CO2 pump located directly upstream of the ejector motive nozzle inlet were analyzed. Based on the experimental data, the maximum COP improvements are 4.64 % and 9.47 % when the ejector and the internal heat exchanger are used, respectively. The CO2 pump, once successfully stabilized, can control the ejector, increase its efficiency by up to 15 % and increase the cooling capacity to a maximum of 6.2 %. Nevertheless, a reduction in COP is measured when the pump is in use; however, unlike the other three different configurations, it was only analyzed under subcritical conditions

If the Walls Could Speak: Artwork for Representational Library Spaces

Artwork featuring diverse styles, cultures, and perspectives can promote inclusivity and representation within library spaces. Our library has partnered with a local Art Foundation to introduce artwork from local artists that reflect the diversity of our student population. Rather than a centrally located exhibition, the art has been integrated into the whole library building to be accessible and inspire reflection and recognition. This lightning talk briefly explains the collaborative project and the value of art in a library space to express diverse voices explored through visual storytelling

Conceptualizing a Teaching Motivation Model for Faculty

This paper presents a Teaching Motivation Model that conceptualizes motivation for faculty teaching. The model was informed by the self-determination theory, the self-control strength model, and the review of the literature on college teaching. The Teaching Motivation Model presents a more comprehensive account of faculty teaching motivation and group factors affecting faculty teaching motivation into three groups: environmental, individual, and institutional-level factors. Ongoing interactions between these mutually interrelated and influential groups of factors may either support or inhibit faculty engagement in a particular method of teaching. The model posits self-control strength, which plays a central role in faculty engagement in an intended form of teaching. Implications for research and practice are included

Business and Financial Management and Audit Control for Large Research Proposals

Overview of the Purdue University business, financial, and human resources operations as evidence of support for faculty to manage externally funded research

The Economics and Productivity of US Cow-Calf Production

We explore US beef cow-calf production in 2018 and estimate net returns, returns to scale, and technical efficiency associated with backgrounding versus nonbackgrounding by size and production system. We determine the relative profitability of cow-calf operations by type, region, and size. Results, using both stochastic production frontier analysis and data envelopment analysis, indicate that larger operations tend to be more scale and technically efficient than smaller operations. While larger operations may be more scale and technically efficient and have lower variable costs per cow, off-farm income helps smaller operations become competitive. The availability of detailed cost of production information in the 2018 Agricultural Resource Management Survey of cattle and calves survey also facilitates identifying competitiveness by region and size as well as important efficiency drivers

Reviewing the need for subject-specific regional professional development opportunities for business librarians

This paper reviews the need for regional professional development opportunities for business librarians, examining the benefits and drawbacks that business librarians experience when attending national, subject-specific, and regional conferences, from the perspective of the creators and organizers of the Midwest Business Librarian Summit (MBLS). Using information gained regarding what benefits librarians seek when considering conference attendance as well as the obstacles or challenges experienced, this paper offers information about extant regional conferences for business librarians as well as suggestions for developing an in-person, subject-specific regional conference targeted toward business librarians

A Deep Learning Framework with Explainable AI for Atmospheric Blocking Detection and Interpretation

Atmospheric blocking is a large-scale quasi-stationary phenomenon in mid-latitude circulation, characterized by persistent high-pressure systems that disrupt the typical west-to-east flow of the jet stream. These systems can cause extreme weather events—such as heatwaves, cold spells, or droughts—that persist for days or even weeks. This study proposes a deep learning framework to predict and interpret the occurrence of atmospheric blocking by integrating geophysical precursors such as geopotential height (Z500), stream function (SF200), and potential vorticity. These features, which are dynamically linked to blocking onset and persistence, serve as inputs to a Convolutional Neural Network model trained on the CESM Large Ensemble (LENS) dataset. After initial training, we apply transfer learning to adapt the model to the ERA5 reanalysis dataset, preserving the feature extractor while retraining the classifier to improve generalization on real-world atmospheric data. To improve model transparency and interpretability, we apply eXplainable AI techniques. These tools provide spatial insights into the CNN\u27s decision-making process, highlighting which atmospheric features are most important for the model’s blocking predictions. By advancing the understanding of mechanisms and indicators of blocking through deep learning and XAI, this work contributes toward more accurate and interpretable weather forecasting models—vital for anticipating and mitigating the societal impacts of extreme weather events

Building a Regional Library-Led Case Competition: Reflections from Librarians and Vendor Partners

Libraries are increasingly involved in supporting and facilitating case competitions, leading to competitions that emphasize decision-making and understanding of a larger ecosystem of information. This paper examines existing literature on the topics of librarian support for case competitions, the growing trend of library-led case competitions, and the expanded role of libraries in support of entrepreneurs, students, and faculty in entrepreneurial programs. The conversation is expanded through a discussion of the Midwest Entrepreneurship Case Competition (MECC), a library-led case competition that prioritized the participation of undergraduate students and grew from a local to a regional event. Vendor engagement, case development, competition format, timeline, and execution are shared and analyzed. Reflections from three stakeholders, including a first-time case competition planner, case competition judge, and vendor partner, enumerate MECC’s benefits to librarianship and student learning, approaches to information literacy, and opportunities for hands-on engagement in the development and marketing of tools. This research demonstrates the value of library-led case competitions as interventions for building transferable business information literacy skills and mechanisms for shaping and furthering collaboration among libraries, librarians, students, and vendors

Skills for Success as a Frontline Supervisor: Focus Group Results

Frontline supervisors (FLS), commonly referred to as foreman/person, play a critical role in the construction industry; they direct craft laborers and oversee production at the workface. They are generally responsible for ensuring that specific construction scopes are completed on time, safely, and with appropriate quality. For the purposes of this paper, a FLS is defined as, “a person that is competent in their trade and leads a team of craft personnel and directs them in their day-to-day activities.” This paper elucidates the key skills and experience required for success in this position based on a thematic analysis of 15 job postings provided by a focus group of five people who understood this definition. Analysis indicates that more than 60% of the postings required job-specific experience and construction knowledge, while about half of the postings required the soft skills of leadership and communication. These insights contribute to the workforce development and construction management bodies of knowledge by explicitly documenting the skills and experience required for success in this rarely discussed role. Based on these findings, construction organizations can self-assess whether they are seeking appropriate skills when advertising FLS positions. Educators can also use these findings to ensure their offerings yield marketability as an FLS