Energy flux measurement from the dissipated energy in capillary wave turbulence

We study experimentally the influence of dissipation on stationary capillary wave turbulence on the surface of a fluid by changing its viscosity. We observe that the frequency power law scaling of the capillary spectrum departs significantly from its theoretical value when the dissipation is increased. The energy dissipated by capillary waves is also measured and found to increase nonlinearly with the mean power injected within the fluid. Here, we propose an experimental estimation of the energy flux at every scale of the capillary cascade. The latter is found to be non constant through the scales. For fluids of low enough viscosity, we found that both capillary spectrum scalings with the frequency and the newly defined mean energy flux are in good agreement with wave turbulence theory. The Kolmogorov-Zakharov constant is then experimentally estimated and compared to its theoretical value.Comment: Physical Review E (2013) submitted to PR

Promoting Intermodal Connectivity at California’s High Speed Rail Stations

High-speed rail (HSR) has emerged as one of the most revolutionary and transformative transportation technologies, having a profound impact on urban-regional accessibility and inter-city travel across Europe, Japan, and more recently China and other Asian countries. One of HSR’s biggest advantages over air travel is that it offers passengers a one-seat ride into the center of major cities, eliminating time-consuming airport transfers and wait times, and providing ample opportunities for intermodal transfers at these locales. Thus, HSR passengers are typically able to arrive at stations that are only a short walk away from central business districts and major tourist attractions, without experiencing any of the stress that car drivers often experience in negotiating such highly congested environments. Such an approach requires a high level of coordination and planning of the infrastructural and spatial aspects of the HSR service, and a high degree of intermodal connectivity. But what key elements can help the US high-speed rail system blend successfully with other existing rail and transit services? That question is critically important now that high-speed rail is under construction in California. The study seeks to understand the requirements for high levels of connectivity and spatial and operational integration of HSR stations and offer recommendations for seamless, and convenient integrated service in California intercity rail/HSR stations. The study draws data from a review of the literature on the connectivity, intermodality, and spatial and operational integration of transit systems; a survey of 26 high-speed rail experts from six different European countries; and an in-depth look of the German and Spanish HSR systems and some of their stations, which are deemed as exemplary models of station connectivity. The study offers recommendations on how to enhance both the spatial and the operational connectivity of high-speed rail systems giving emphasis on four spatial zones: the station, the station neighborhood, the municipality at large, and the region

Nonlinear waves on the surface of a fluid covered by an elastic sheet

We experimentally study linear and nonlinear waves on the surface of a fluid covered by an elastic sheet where both tension and flexural waves take place. An optical method is used to obtain the full space-time wave field, and the dispersion relation of waves. When the forcing is increased, a significant nonlinear shift of the dispersion relation is observed. We show that this shift is due to an additional tension of the sheet induced by the transverse motion of a fundamental mode of the sheet. When the system is subjected to a random noise forcing at large scale, a regime of hydro-elastic wave turbulence is observed with a power-law spectrum of the scale in disagreement with the wave turbulence prediction. We show that the separation between relevant time scales is well satisfied at each scale of the turbulent cascade as expected theoretically. The wave field anisotropy, and finite size effects are also quantified and are not at the origin of the discrepancy. Finally, the dissipation is found to occur at all scales of the cascade contrary to the theoretical hypothesis, and could thus explain this disagreement.Comment: Journal of Fluid Mechanics (2013

Digging through the Heart of Reunified Berlin: Unbundling the Decision-Making Process for the Tiergarten-Tunnel Mega-Project

The Berlin Tiergarten tunnel project (VZB) consisted of a joint planning approval procedure for one road and several rail tunnels (inter-city, metro rail and city subway). The tunnels lead through the heart of re-unified Berlin, starting at the site of the new Central Railway Station, cutting underneath the River Spree and the new Federal government quarter, as well the Tiergarten Park and the new entertainment complexes at Potsdamer Platz. This paper traces the decision-making processes for this crucial post-Berlin Wall mega-project, and raises important questions regarding optimistic forecasts, cost overruns, the role of prestige in large infrastructure projects, and the limits of public review procedures. It provides particular insights into a complex case where multiple urban transport mega-projects were bundled together for joint approval and implementation.&nbsp

ChatGPT: The New Business Librarian?

With the early 2023 public release of ChatGPT, natural language models and generative artificial intelligence (AI) have been making waves across numerous industries and academic communities. Many are speculating on the impact it will have in the education industry, including libraries. Librarians may already be dealing with patrons whose inquiries are a result of information generated by AI, and some may be adopting the tool themselves to augment various work processes. This talk will briefly cover takeaways of an ongoing research project at the University of Notre Dame’s Thomas Mahaffey Jr. Business Library assessing the capabilities of ChatGPT when applied to research assistance questions in the Business subject areas. This talk will focus on some of the basic takeaways of the project which involved asking ChatGPT a sample of real research assistance questions asked at the business library between the years 2018 and 2022. On the whole, how well does ChatGPT fulfill the role of conducting business specific research assistance, and are there any ways that generative AI could ethically or efficiently be applied to Business Librarianship

An Organic Approach to Instruction: the Business Problem Solving Case

In the past year, the Thomas Mahaffey Jr. Business Library at the University of Notre Dame provided instruction for a unique course offered by the Mendoza College of Business, Business Problem Solving. Business Problem Solving immerses students in a challenging environment working as teams to resolve a series of cases created by real consulting companies. Teams in each course section compete with each other to see who can produce the most well researched solution for problem posed by the company. For this course, instructors reached out to the library to introduce students to library resources that could augment their case solutions. The structure of the course posed unique challenges to point of need library instruction in the following domains: fluidity of the course curriculum, reliance on external companies for case materials, and the interdisciplinary nature of cases. This talk covers the impact of these challenges as they relate to library instruction in addition to the Mahaffey Business Library’s solutions for providing effective library instruction in such an environment

Direct numerical simulations of capillary wave turbulence

This work presents Direct Numerical Simulations of capillary wave turbulence solving the full 3D Navier Stokes equations of a two-phase flow. When the interface is locally forced at large scales, a statistical stationary state appears after few forcing periods. Smaller wave scales are generated by nonlinear interactions, and the wave height spectrum is found to obey a power law in both wave number and frequency in good agreement with weak turbulence theory. By estimating the mean energy flux from the dissipated power, the Kolmogorov-Zakharov constant is evaluated and found to be compatible with the exact theoretical value. The time scale separation between linear, nonlinear interaction and dissipative times is also observed. These numerical results confirm the validity of weak turbulence approach to quantify out-of equilibrium wave statistics.Comment: Physical Review Letters (2014) in pres

A Comparative Analysis of High-Speed Rail Station Development into Destination and Multi-Use Facilities: The Case of San Jose Diridon

As a burgeoning literature on high-speed rail development indicates, good station-area planning is a very important prerequisite for the eventual successful operation of a high-speed rail station; it can also trigger opportunities for economic development in the station area and the station-city. At the same time, “on the ground” experiences from international examples of high-speed rail stations can provide valuable lessons for the California high-speed rail system in general, and the San Jose Diridon station in particular. This study identifies and draws lessons from European HSR stations that share similarities across several criteria with the San Jose area context. From an initial consideration of twenty European HSR stations, the researchers chose five stations for in depth case studies: Euralille and Lyon Part Dieu in France, Rotterdam Centraal and Utrecht Centraal in the Netherlands, and Torino Porta Susa in Italy. Additionally, the study drew information from relevant local actors and stakeholders to better tailor recommendations to the particular California context.Through the undertaking of different research tasks–literature review, case studies of European railway stations, survey of existing station plans and other planning documents for the Diridon station, station area analysis, and interviews with station area planners and designers–the study compiles timely recommendations for the successful planning of the Diridon station and other stations along the California high-speed rail corridor

Aquaporins with anion/monocarboxylate permeability: mechanisms, relevance for pathogen–host interactions

Classically, aquaporins are divided based on pore selectivity into water specific, orthodox aquaporins and solute-facilitating aquaglyceroporins, which conduct, e.g., glycerol and urea. However, more aquaporin-passing substrates have been identified over the years, such as the gasses ammonia and carbon dioxide or the water-related hydrogen peroxide. It became apparent that not all aquaporins clearly fit into one of only two subfamilies. Furthermore, certain aquaporins from both major subfamilies have been reported to conduct inorganic anions, such as chloride, or monoacids/monocarboxylates, such as lactic acid/lactate. Here, we summarize the findings on aquaporin anion transport, analyze the pore layout of such aquaporins in comparison to prototypical non-selective anion channels, monocarboxylate transporters, and formate-nitrite transporters. Finally, we discuss in which scenarios anion conducting aquaporins may be of physiological relevance

Tundale’s Vision: Socialization in 12th Century Ireland

The purpose of this project is to explore the historical image of Hell in Medieval Europe as an agent of socialization for illiterate Christian communities. The project focuses on a literary work, Tundale’s Vision, written in 1149 C.E in Cashel, Ireland. Tundale’s Vision came from a genre of vision literature derived from popular oracular folk tradition surrounding the image of Hell that served the purpose of socializing Christian communities to certain social norms and stigmas presented by the author. Vision literature would be used by preachers in vernacular sermons throughout the Medieval period in order to reinforce moral and social messages presented in to their congregations, and it drew much of its themes and imagery from folk traditions in order to be more relatable to local communities. This research provides a historical context from which this genre of literature emerged including a discourse on how it gained power as an agent of socialization in Medieval Europe. Time is devoted to the historical state of what are generally considered primary agents of socialization in human societies throughout Medieval Europe, and research reveals that much of these agents, aside from religion, were inaccessible to the majority of Medieval Europeans, especially those of the lower class. Additionally, this project provides information on the rise in popularity of the artistic image of Hell in the Medieval period. The analysis of Tundale’s Vision, a work that emerged from this environment saturated with artistic depictions of Hell, reconstructs potential social norms and stigmas of 12th century Ireland relating to a contemporary reform movement within the Irish Christian church. This analysis provides the historical origin of many images commonly associated with the popular Medieval conception of Hell as it appears in Tundale’s Vision, and it analyzes the use of the fear of a painful afterlife in order spread and reinforce ideals presented by the Christian Church. Much of this project draws from the scholarly works of Gwenfair Adams and John Seymour who produced research concerning Tundale’s Vision, other works of vision literature, and their impact on Medieval Christian communities. The power of religious artwork in the process of socialization in Medieval Ireland should become apparent throughout this work