Visualisation and quantitative analysis of the near nozzle formation and structure of a high pressure water jet in air and water

[EN] High pressure water jets (HPWJ) with Reynolds numbers in the scale of 104 are visualised by high speed photography in air and water. Moreover, suitable measurement techniques are tested and verified by quantitative analysis of the emerging jet to identify the influence of the surrounding fluid on the HPWJ. The HPWJ process known from industrial applications can be adapted to the field of rock drilling. In this specific case, the HPWJ is used to cut and destroy rock in deep geothermal reservoirs. The process is known as jet drilling. Although there have been research activities in this field, the process itself is not well understood so far and practical applications are rare. Therefore, the aim of our work is the visualisation of the process to increase the knowledge of waterjet and rock interactions. High speed photography in terms of shadowgraph experiments is used for visualisation. Moreover, an estimation of the fluid velocity on the boundary of the HPWJ in air is performed. For this, the shadowgraph images are evaluated with the double-frame technique well known with particle image velocimetry (PIV). Analysis of both the structure and the velocity distribution of the HPWJ in water is done by combined PIV and laser induced fluorescence (LIF) analysis with fluorescent dye.This work is being funded through the “FH-Struktur2016” venue for universities of applied sciences by the ministry for innovation, science and research of the state of Nordrhein-Westfalen, Germany (AZ: 322-8.03.04.02).Jasper, S.; Hussong, J.; Lindken, R. (2017). Visualisation and quantitative analysis of the near nozzle formation and structure of a high pressure water jet in air and water. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 947-953. https://doi.org/10.4995/ILASS2017.2017.4736OCS94795

Diet of the Invasive Lionfish Pterois sp. in Broward County, Florida

The geographic range of invasive lionfish Pterois sp. currently extends throughout the Greater Caribbean in the western North Atlantic, prompting concerns about the impacts of its predation on local ecosystems. We focused on dietary habits of lionfish in Broward County, Florida, where there is only limited, anecdotal information on the species’ prey selection. Diet was determined using percent number, percent occurrence and percent weight, as well as the composite index of relative abundance (%IRI). A high percent teleost diet was documented during the third quarter (July-September) and a high crustacean diet in the fourth quarter (October-December), but seasonal effects by quarter or wet-dry analyses were insignificant. We observed an ontogenetic shift from a mainly crustacean diet to one consisting of mainly teleost fishes: the smallest lionfish size group (5-10 cm) had a 100% crustacean diet, whereas the largest size group (35-40 cm) had a 77% teleost and 23% crustacean diet. Our study results found no evidence that lionfish consumed commercially or recreationally targeted teleost species in these nearshore reef habitats

3D-printed structured adsorbents for molecular separation

Most adsorbents are produced as porous, micron-sized powder materials and are thus not suitable to be directly used in adsorption processes. In order to avoid excessive pressure drop during flow of gas or liquid streams through a packed bed of adsorbent, these powders are shaped into larger particles or structured adsorbents. Extrudates, beads or pellets with a size of several millimeters are widely used in industrial processes. The most important disadvantages of such particles include the relatively large pressure drop they generate at high flow rates and the presence of mass transfer limitations as a result of slow diffusion of molecules to the core of the particles. A trade-off between these two effects limits the possibilities to optimize packed bed adsorptive separation processes; e.g. decreasing pellet size allows to reduce mass transfer limitations but this in turn leads to larger pressure drops. In practice, bed geometry (length/width of the packed bed) is adapted to limit pressure drop. Nevertheless, classical packed beds are not ideal for processes in which very short cycle times or very high gas or liquid velocities are required. Other types of adsorbent formulation that allow eliminating the limitations mentioned above are thus of large interest. Monolithic adsorbents are superior to classical packed bed adsorbents in terms of pressure drop and mass transfer kinetics. The honeycomb structure, mostly known from catalytic exhaust treatment in the automotive industry, is a well-known example, but monolithic structures are also used in liquid chromatography and heterogeneous catalysis. Nevertheless, the production of monoliths is complicated; classical extrusion processes only offer a very limited flexibility in the geometric properties of the monolith while polymerization processes are not suited for the production of materials for high temperature applications. Please click Additional Files below to see the full abstract

Impact demagnetization of the Martian crust: Current knowledge and future directions

The paleomagnetism of the Martian crust has important implications for the history of the dynamo, the intensity of the ancient magnetic field, and the composition of the crust. Modification of crustal magnetization by impact cratering is evident from the observed lack of a measurable crustal field (at spacecraft altitude) within the youngest large impact basins (e.g., Hellas, Argyre and Isidis). It is hoped that comparisons of the magnetic intensity over impact structures, forward modeling of subsurface magnetization, and experimental results of pressure-induced demagnetization of rocks and minerals will provide constraints on the primary magnetic mineralogy in the Martian crust. Such an effort requires: (i) accurate knowledge of the spatial distribution of the shock pressures around impact basins, (ii) crustal magnetic intensity maps of adequate resolution over impact structures, and (iii) determination of demagnetization properties for individual rocks and minerals under compression. In this work, we evaluate the current understanding of these three conditions and compile the available experimental pressure demagnetization data on samples bearing (titano-) magnetite, (titano-) hematite, and pyrrhotite. We find that all samples demagnetize substantially at pressures of a few GPa and that the available data support significant modification of the crustal magnetic field from both large and small impact events. However, the amount of demagnetization with applied pressure does not vary significantly among the possible carrier phases. Therefore, the presence of individual mineral phases on Mars cannot be determined from azimuthally averaged demagnetization profiles over impact basins at present. The identification of magnetic mineralogy on Mars will require more data on pressure demagnetization of thermoremanent magnetization and forward modeling of the crustal field subject to a range of plausible initial field and demagnetization patterns.United States. National Aeronautics and Space Administration (NNG04GD17G)United States. National Aeronautics and Space Administration (NNX07AQ69G)United States. National Aeronautics and Space Administration (NNX06AD14G

Local magnetism in MnSiPt rules the chemical bond

A crystal structure can be understood as a result of bonding interactions (covalent, ionic, van der Waals, etc.) between the constituting atoms. If the forces caused by these interactions are equilibrated, the so-stabilized crystal structure should have the lowest energy. In such an atomic configuration, additional weaker atomic interactions may further reduce the total energy, influencing the final atomic arrangement. Indeed, in the intermetallic compound MnSiPt, a 3D framework is formed by polar covalent bonds between Mn, Si, and Pt atoms. Without taking into account the local spin polarization of manganese atoms, they would form Mn–Mn bonds within the framework. Surprisingly, the local magnetic moments of manganese prevent the formation of Mn–Mn bonds, thus changing decisively and significantly the final atomic arrangement.Among intermetallic compounds, ternary phases with the simple stoichiometric ratio 1:1:1 form one of the largest families. More than 15 structural patterns have been observed for several hundred compounds constituting this group. This, on first glance unexpected, finding is a consequence of the complex mechanism of chemical bonding in intermetallic structures, allowing for large diversity. Their formation process can be understood based on a hierarchy of energy scales: The main share is contributed by covalent and ionic interactions in accordance with the electronic needs of the participating elements. However, smaller additional atomic interactions may still tip the scales. Here, we demonstrate that the local spin polarization of paramagnetic manganese in the new compound MnSiPt rules the adopted TiNiSi-type crystal structure. Combining a thorough experimental characterization with a theoretical analysis of the energy landscape and the chemical bonding of MnSiPt, we show that the paramagnetism of the Mn atoms suppresses the formation of Mn–Mn bonds, deciding between competing crystal structures

Exciton level structure and dynamics in tubular porphyrin aggregates

We present an account of the optical properties of the Frenkel excitons in self-assembled porphyrin tubular aggregates that represent an analog to natural photosynthetic antennae. Using a combination of ultrafast optical spectroscopy and stochastic exciton modeling, we address both linear and nonlinear exciton absorption, relaxation pathways, and the role of disorder. The static disorder-dominated absorption and fluorescence line widths show little temperature dependence for the lowest excitons (Q band), which we successfully simulate using a model of exciton scattering on acoustic phonons in the host matrix. Temperature-dependent transient absorption of and fluorescence from the excitons in the tubular aggregates are marked by nonexponential decays with time scales ranging from a few picoseconds to a few nanoseconds, reflecting complex relaxation mechanisms. Combined experimental and theoretical investigations indicate that nonradiative pathways induced by traps and defects dominate the relaxation of excitons in the tubular aggregates. We model the pump?probe spectra and ascribe the excited-state absorption to transitions from one-exciton states to a manifold of mixed one- and two-exciton states. Our results demonstrate that while the delocalized Frenkel excitons (over 208 (1036) molecules for the optically dominant excitons in the Q (B) band) resulting from strong intermolecular coupling in these aggregates could potentially facilitate efficient energy transfer, fast relaxation due to defects and disorder probably present a major limitation for exciton transport over large distances. We present an account of the optical properties of the Frenkel excitons in self-assembled porphyrin tubular aggregates that represent an analog to natural photosynthetic antennae. Using a combination of ultrafast optical spectroscopy and stochastic exciton modeling, we address both linear and nonlinear exciton absorption, relaxation pathways, and the role of disorder. The static disorder-dominated absorption and fluorescence line widths show little temperature dependence for the lowest excitons (Q band), which we successfully simulate using a model of exciton scattering on acoustic phonons in the host matrix. Temperature-dependent transient absorption of and fluorescence from the excitons in the tubular aggregates are marked by nonexponential decays with time scales ranging from a few picoseconds to a few nanoseconds, reflecting complex relaxation mechanisms. Combined experimental and theoretical investigations indicate that nonradiative pathways induced by traps and defects dominate the relaxation of excitons in the tubular aggregates. We model the pump?probe spectra and ascribe the excited-state absorption to transitions from one-exciton states to a manifold of mixed one- and two-exciton states. Our results demonstrate that while the delocalized Frenkel excitons (over 208 (1036) molecules for the optically dominant excitons in the Q (B) band) resulting from strong intermolecular coupling in these aggregates could potentially facilitate efficient energy transfer, fast relaxation due to defects and disorder probably present a major limitation for exciton transport over large distances

Critical Path for Project Development

Overseeing the delivery of highway projects at the Kentucky Transportation Cabinet (KYTC) requires the successful coordination of activities and inputs from multiple external agencies and members of the agency’s Project Development team, who have varied disciplinary backgrounds. Despite the complexity of project delivery, the Cabinet presently does not estimate hours and project milestone dates until after it has selected a design consultant. Moving forward KYTC should explore requiring consultants to develop a critical path method (CPM) schedule. To facilitate this process, this report describes a methodology for producing CPMs for design contracts/projects based on procedures outlined in A Guide to the Project Management Body of Knowledge. In addition to reviewing the CPM, this document includes critical path templates that are representative of the Cabinet’s project design process. Templates were developed with the assistance of KYTC experts knowledgeable in areas such as project management, environmental processes, utilities, right of way, and highway design. Work-breakdown units, templates, and Gantt charts for three project contexts were developed: 1) Rural Federal Bridge Replacement (Categorical Exclusion I), 2) Urban Federal Bridge Replacement (Categorical Exclusion I), and 3) 4-Mile Rural Road Widening into Urban Intersection (Environmental Assessment, Finding of No Significant Impact). An in-depth glossary contains detailed explanations of work-breakdown units and flags issues and challenges that merit close attention during project development. With recourse to the tools and templates presented in this report, project managers and consultants can pursue project management in an organized manner and be ready to deal with any contingencies that may arise