Numerical validation of the two-scale actuator disc theory for marine turbine arrays

The challenge in the hydrodynamic modelling of tidal and marine turbine farms is to take into account the interaction of flow events across a wide range of scales, such as the blade scale, turbine scale, array scale and regional scale. Whilst the interaction of the blade and turbine scales can be studied using the classical Blade-Element-Momentum (BEM) theory, no basic theory was available until recently to describe the interaction of the turbine and larger scales. The two-scale actuator disc theory (ADT), first proposed in 2012 by Nishino and Willden, explains the interaction of the turbine and array scales at a fundamental level; however, its validity or applicability to real problems has only partially been confirmed. Hence in this study we perform 3D RANS simulations of single and double rows of porous discs (8 discs for each row) in the middle of a shallow open channel with a vertically sheared flow. The simulation results are shown to agree qualitatively with the two-scale ADT and importantly, the optimal intra-disc spacing predicted by the simulations (to maximise the total power) agrees well with the theory, for both single- and double-row cases

ESPACIO

Edgar Perez Peña (He, Him, His) is a Queer, Chicanx contemporary figurative painter, who lives and works in the Los Angeles County. A native of Los Angeles, California, his paintings, and assemblages are a strong combination of process, materials, and content that displays his fascination on how physical/psychological space (from where he resides), reflects on the Queer Brown body and its comfort/discomfort in relation to public and private space. Peña looks at his artistic practice as an opportunity to explore the human condition from the Queer and Brown perspective as well the beginning of healing through the meditative process of painting. Peña’s body functions as a vessel that secures, protects, and feels. His color choices, textures and arrangements lead the viewer in a reflective state, curiosity, and dwelling, while his surfaces show no signs of an end. He also looks at his ideas of being unfinished fragments that take form into assemblages, drawings, paintings, and photographs in which his paintings and assemblages are used to question our social constructs, gender performance as well how space plays a crucial part on our physical and psychological behavior. Espacio (2023) is a group of mix media paintings that takes place in a state of reflection where themes of private and public space explore the human condition of the Queer and Brown body back to the self, with others and space

Developing a Resilient Network Ambidexterity Scale

The purpose of this study was to develop a resilient network ambidexterity scale. While numerous research efforts have considered the dimensions of social capital, resilience, and adaptive capacity to evaluate organizations and communities, few have explored social network indicators within organizations that can be used to mobilize ambidextrous strategies during times of disruption. The emphasis here was to understand the tendencies and behaviors that networks possess to sustain or achieve success along the parallel strategies of optimization and exploration. This study progressed in three specific phases toward filling this void in organizational development literature, using a mixed-methods approach. Phase 1 was the development of the item pool and analysis of the scale to establish face and content validity. Phase 2 included administering an online survey to 344 participants. Data collected were analyzed using exploratory factor analysis, followed by a partial confirmatory factor analysis These revealed a two-factor solution central to identifying resilient network ambidexterity: Optimizing Organizational Boundaries and Exploring Novelty. Phase 3 involved getting feedback on the revised scale from organizational leaders and practitioners working in innovative fields to refine the final RNA instrument. This research made connections between resilience and ambidexterity in organizations through ongoing inquiry on ways that fusing distinct paradigms impacts organizational outcomes. The development of this scale can serve as a useful tool for organizations to assess their level of resilience and mobilize the features of optimization and exploration. This dissertation is available in open access at AURA: Antioch University Repository and Archive, http://aura.antioch.edu/ and Ohiolink ETD Center, https://etd.ohiolink.edu

Twisted Covariant Form Hierarchies: From Hidden Symmetries in M-theory to Anomalies in Heterotic Backgrounds.

In this thesis, we compute the twisted covariant form hierarchies (TCFHs) of minimal supergravity theories in four and five dimensions, as well as, eleven-dimensional super-gravity and the internal space of its warped AdS backgrounds. As a consequence, the form bilinears satisfy a generalised conformal Killing-Yano equation with respect to the TCFH connection. Then, we find the (hidden) symmetries generated by the form bilin-ears in spinning particle actions propagating in certain supersymmetric backgrounds of D = 4, N = 2 and D = 5, N = 1 minimal supergravities, M-brane backgrounds which include the M2-brane, M5-brane, pp-wave and KK-monopole, maximal supersymmetric AdS backgrounds and some AdS backgrounds that arise as near horizon geometries of intersecting M-branes. In addition, we explore whether the form bilinears are sufficient to prove the integrability of particle probe dynamics on M-brane backgrounds. More-over, we show that the covariantly constant forms of heterotic backgrounds with SU(2) and SU(3) holonomy generate a W-symmetry algebra in two-dimensional non-linear su-persymmetric sigma models with the previous backgrounds as target spaces and analyse the consistency conditions of the chiral anomalies arising from all symmetry generators required for the closure of the algebra

Chronic Toxicity of Binary Metal Mixtures of Cadmium-Zinc and Cadmium-Nickelon Daphnia magna

This study characterizes binary-metal mixture effects of cadmium (Cd2+) + zinc (Zn2+) and Cd2+ + nickel (Ni2+) on Daphnia magna. Although acute studies have shown protective Ni2+ (Traudt et al. 2016) and Zn2+ effects (Meyer et al. 2015) against Cd2+ toxicity, no study has fully characterized a protective effect on D. magna at several endpoints (survival, reproduction, growth, and accumulation) on a chronic study. In this study, the titration design was selected to characterize the 21 day (21-d) chronic effects of the binary-metal mixtures on survival, growth, reproduction, and metal accumulation in D. magna. Using this design, increasing concentrations of Zn2+ (10, 20, 40, 80, 120, 160 and 200µg/L) and Ni2+ (20, 40, 80, 100, 120, 140, and 160µg/L) were titrated against a constant concentration of 1.5µg/L Cd2+. A single-metal assay (Zn2+/Ni2+ alone), a Cd2+ alone treatment, and a control treatment were concurrently conducted for comparison. The results in this thesis demonstrate that Cd2+ alone was highly toxic to D. magna. In a mixture with Cd2+ and Zn2+, sublethal concentrations of 10 and 20µg/L Zn2+ were consistently insufficient to protect D. magna from chronic Cd2+ toxicity since Cd2+ toxic effects were observed on the survival, reproductive, and growth endpoints (Figs. 1, 2, 9), whereas mixtures containing 40, 80, and 120µg/L Zn2+ provided strong protective effects to D. magna at all the endpoints examined. Higher Zn2+ concentrations of 160 and 200µg/L exceeded the necessary concentrations needed to protect D. magna, and no protective effects were observed. In contrast, sublethal and moderate Ni2+ concentrations of 20, 40, and 80µg/L were found to strongly protect D. magna from chronic Cd2+ toxicity, whereas higher Ni2+ concentrations (≥100µg/L) exceeded the necessary concentration needed to protect D. magna, and Ni2+ protective effects were absent. Interestingly, 1.5µg/L Cd2+ was found to be protective in the Cd2+-Ni2+ mixture containing 100µg/L Ni2+. Additionally, no concentration of Ni2+ or Zn2+ was found to provide complete protective effects to D. magna (i.e. 100% protective effects). Therefore, suggesting that no concentration of Zn2+ or Ni2+ used in this study, entirely outcompeted the binding of Cd2+ ions to the biotic ligand. Embryos analyzed for morphological alterations in both the Cd2+-Zn2+ and Cd2+-Ni2+ mixtures demonstrate severe developmental defects. The results of the present study are useful for development of environmental quality guidelines for metal mixtures

Identifying the true European ‘low-cost airports'

This paper discusses the long-term effects of low-cost carrier (LCC) presence at European airports and identifies the airports that have benefited the most from LCC consolidation during the current century. The research uses ‘LCC Market Share’, in terms of seats, to measure the relative importance of LCCs within each airport; and introduces ‘EU LCA Rank’ as a normalised metric of the capacity share of every airport in the European low-cost segment. It evaluates the trends between 2001 and 2018 in a sample of the 300 largest European airports, by total seats in 2018, using OAG supply information (seats by carrier). Results highlight the role that LCCs have played in boosting the growth of airports, both primary and secondary, that were keen to appreciate the development of the low-cost segment earlier. Indeed, despite the fact that LCCs have put many airports on the European map, during the second half of the period of analysis growth has been more significant for major airports. In that sense, this paper contributes a better understanding of the recent dynamics in European LCCs choice of airports and, in particular, the long-term effects that this disruptive business model have had for airports

Protein imprinting by means of alginate-based polymers

Methods of preparing molecularly imprinted polymers are provided. In one embodiment, a method comprises providing a solution comprising a template molecule; and forming a product comprising calcium alginate in the presence of the template molecule so that the template molecule is imprinted in the product.Board of Regents, University of Texas Syste