An experimental approach to submarine canyon evolution

We present results from a sandbox experiment designed to investigate how sediment gravity flows form and shape submarine canyons. In the experiment, unconfined saline gravity flows were released onto an inclined sand bed bounded on the downstream end by a movable floor that was used to increase relief during the experiment. In areas unaffected by the flows, we observed featureless, angle-of-repose submarine slopes formed by retrogressive breaching processes. In contrast, areas influenced by gravity flows cascading across the shelf break were deeply incised by submarine canyons with well-developed channel networks. Normalized canyon long profiles extracted from successive high-resolution digital elevation models collapse to a single profile when referenced to the migrating shelf-slope break, indicating self-similar growth in the relief defined by the canyon and intercanyon profiles. Although our experimental approach is simple, the resulting canyon morphology and behavior appear similar in several important respects to that observed in the field

Transient erosion in the Valencia Trough turbidite systems, NW Mediterranean Basin

Submarine canyons can efficiently drain sediments from continental margins just as river systems do in subaerial catchments. Like in river systems, submarine canyons are often arranged as complex drainage networks that evolve from patterns of erosion and deposition. In the present paper we use a morphometric analysis of submarine canyon-channel long-profiles to study the recent sedimentary history of the Valencia Trough turbidite system (VTTS) in the NW Mediterranean Sea. The VTTS is unique in that it drains sediment from margins with contrasting morphologies through a single "trunk" conduit, the Valencia Channel. The Valencia Channel has been active since the late Miocene, evolving in response to Plio-Quaternary episodes of erosion and deposition. The integrated analysis of long-profiles obtained from high-resolution bathymetric data across the entire turbidite system shows evidence for transient canyon incision in the form of knickpoints and hanging tributaries. Multiple factors appear to have triggered these periods of incision. These include a large debris flow at 11,500 yr BP that disrupted the upper reaches of the VTTS and glacio-eustatic lowstands that forced shifting of sediment input to the VTTS. Based on these inferences, long-term time-averaged incision rates for the Valencia Channel have been estimated. The evidence we present strongly suggests that Foix Canyon has played a key role in the drainage dynamics of the VTTS in the past. This study builds conceptually on a recent modeling study that provides a morphodynamic explanation for the long-term evolution of submarine canyon thalweg profiles. The procedure and results from this work are of potential application to other submarine sediment drainage systems, past and present, including those containing mid-ocean type valleys like the Valencia Channel

Direct characterization of photo-induced lattice dynamics in BaFe₂As₂

Ultrafast light pulses can modify electronic properties of quantum materials by perturbing the underlying, intertwined degrees of freedom. In particular, iron-based superconductors exhibit a strong coupling among electronic nematic fluctuations, spins and the lattice, serving as a playground for ultrafast manipulation. Here we use time-resolved X-ray scattering to measure the lattice dynamics of photoexcited BaFe$_{2}$As$_{2}$. On optical excitation, no signature of an ultrafast change of the crystal symmetry is observed, but the lattice oscillates rapidly in time due to the coherent excitation of an A$_{1g}$ mode that modulates the Fe–As–Fe bond angle. We directly quantify the coherent lattice dynamics and show that even a small photoinduced lattice distortion can induce notable changes in the electronic and magnetic properties. Our analysis implies that transient structural modification can be an effective tool for manipulating the electronic properties of multi-orbital systems, where electronic instabilities are sensitive to the orbital character of bands

Integrated motor drives: state of the art and future trends

With increased need for high power density, high efficiency and high temperature capabilities in Aerospace and Automotive applications, Integrated Motor Drives (IMD) offers a potential solution. However, close physical integration of the converter and the machine may also lead to an increase in components temperature. This requires careful mechanical, structural and thermal analysis; and design of the IMD system. This paper reviews existing IMD technologies and their thermal effects on the IMD system. The effects of the power electronics (PE) position on the IMD system and its respective thermal management concepts are also investigated. The challenges faced in designing and manufacturing of an IMD along with the mechanical and structural impacts of close physical integration is also discussed and potential solutions are provided. Potential converter topologies for an IMD like the Matrix converter, 2-level Bridge, 3-level NPC and Multiphase full bridge converters are also reviewed. Wide band gap devices like SiC and GaN and their packaging in power modules for IMDs are also discussed. Power modules components and packaging technologies are also presented

P-Type Silicon Strip Sensors for the new CMS Tracker at HL-L-HC

Abstract: The upgrade of the LHC to the High-Luminosity LHC (HL-LHC) is expected to increase the LHC design luminosity by an order of magnitude. This will require silicon tracking detectors with a significantly higher radiation hardness. The CMS Tracker Collaboration has conducted an irradiation and measurement campaign to identify suitable silicon sensor materials and strip designs for the future outer tracker at the CMS experiment. Based on these results, the collaboration has chosen to use n-in-p type silicon sensors and focus further investigations on the optimization of that sensor type

Housing and integration of internally displaced persons: The case of Ukraine in 2018

Housing is a widely recognized yet understudied domain of integration of internally displaced persons (IDPs) into their new communities. This article examines the role of housing for integration of Ukrainian IDPs displaced by Russia-fueled political violence in Eastern Ukraine that started in 2014 or by Russia's annexation of Crimea that year. In Ukraine, housing holds particular significance for integration because homeownership is both widespread and a vital source of people's sense of wellbeing, security, and normalcy. Our evidence comes from an original 2018 survey of housing experiences of both IDPs and long-term residents in IDPs' new localities. The survey design enables us to assess housing integration relationally, by comparing gaps in housing status and subjective housing-related wellbeing between IDPs and locals. We find that for IDPs in protracted displacement, deprivation of culturally normative housing conditions, particularly homeownership, impeded both material and experiential housing integration. Disparities in housing status drive differences in subjective experience, ranging from satisfaction with one's housing to feeling at home in one's community. These results from our 2018 study may help anticipate challenges of the massive, nationwide displacement crisis precipitated by Russia's 2022 invasion of Ukraine. Whether Ukrainians resettle in new communities or return to their old ones, divisions between those who have homes to return to and those who do not are likely to be salient. Policies aimed at restoring housing resources, particularly pathways to homeownership, will be essential to rebuilding Ukraine. Copyright © 2023 Zavisca, Mitchneck and Gerber.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Decision support for spatially targeted livestock policies: Diverse examples from Uganda and Thailand

Public policies are needed to guide livestock sector¿s changes along a path that is sustainable in economic, social and environmental terms. These policies should include multiple development objectives and be adapted to location-specific contexts. Policy makers need assistance in dealing with such complex decisions. Spatial information can be integrated in decision support tools to support policy making, and is becoming increasingly available in the developing world. Spatial information, however, has seldom been used in livestock sector policy formulation because policy makers generally do not have access to resources for spatial modelling. The objective of this paper is to bridge this gap by proposing an approach to consolidating and analysing spatial information in the context of limited modelling resources. Rooted in practical experience, a method is proposed that combines two multiple criteria decision-making techniques (weighted linear combination and analytical hierarchical processes), parameterised in a participatory process and implemented in a GIS. The method is tested in two different contexts: support to single objective decision-making for targeting trypanosomiasis control interventions in Uganda, and support to multiple objective decision-making for spatial planning of livestock production development in Thailand. The results show the advantages of such an approach, in terms of stakeholder involvement and practical application to support decision-making, but also highlight two shortcomings: dependence on high quality data and uncertainty with regard to the decision rule. While the former will be addressed as digital information becomes increasingly available, the latter, embedded in any decision-making process, calls for thorough sensitivity analyses and careful scrutiny of results