A novel algorithm for a continuous and fast 3D projection of points on triangulated surfaces for CAM/CAD/CAE applications

n/

Isotopic Analysis of Purple Sulfur Bacteria and the Environmental Conditions of Lakes in Indiana and the Pacific Northwest: Water Column Characterizations for Use in Developing a Water Column Profiling Device

poster abstractA better understanding of purple sulfur bacterial geochemical signatures within natural anoxic lakes will provide essential information for the fabrication of a device to isolate and sample the biomass. Purple sulfur bacteria are sulfide (H2S) oxidizing phototropic organisms. They utilize the process of anoxygenic photosynthesis, the reaction of a reducing agent other than water (H2O) and light energy, to produce chemical energy. Dissolved oxygen inhibits the anaerobic respiration of the bacteria causing blooms, or clusters of cellular mass, to form in very restricted conditions. Sulfide is produced by another class of microorganisms called sulfate reducing bacteria. Purple sulfur bacteria must form near the transitional layer between aerobic and anaerobic water (known as the chemocline); at a depth light can reach (photic zone); and in the presence of reduced sulfur. Environments conducive to the development of purple sulfur bacteria can be further understood by isotopic analysis. Samples of lake water from various depths were taken and filtered to isolate the bacteria, and preserve the dissolved sulfate and sulfide. Sulfate was precipitated as BaSO4, and sulfide was extracted using acid volatile extraction (AVS) to trap Ag2S for analysis using mass spectrometry. Sulfur and oxygen isotopes in the samples allow for a comparison between Northern Indiana and Pacific Northwest lakes. Research is ongoing, but the lakes in Indiana have higher lower concentrations of sulfate (~10mM) compared to the Pacific Northwestern lakes (20 to 100mM). Sulfide concentrations are extremely high in the Pacific Northwest lakes (up to 30 mM), possibly reflecting high rates of sulfate reduction and high concentrations of sulfate. Combined, this research will give insight on the nature of anoxic bacterial systems and how they change sulfur isotope composition. The research also provides the opportunity to understand the sedimentary record of the geologic past

First Order Description of D=4 static Black Holes and the Hamilton-Jacobi equation

In this note we discuss the application of the Hamilton-Jacobi formalism to the first order description of four dimensional spherically symmetric and static black holes. In particular we show that the prepotential characterizing the flow coincides with the Hamilton principal function associated with the one-dimensional effective Lagrangian. This implies that the prepotential can always be defined, at least locally in the radial variable and in the moduli space, both in the extremal and non-extremal case and allows us to conclude that it is duality invariant. We also give, in this framework, a general definition of the ``Weinhold metric'' in terms of which a necessary condition for the existence of multiple attractors is given. The Hamilton-Jacobi formalism can be applied both to the restricted phase space where the electromagnetic potentials have been integrated out as well as in the case where the electromagnetic potentials are dualized to scalar fields using the so-called three-dimensional Euclidean approach. We give some examples of application of the formalism, both for the BPS and the non-BPS black holes.Comment: A clarifying discussion on the existence of the prepotential and a comment on multiple attractors are added; typos corrected, references adde

Effects of anisotropic and isotropic LIPSS on polymer filling flow and wettability of micro injection molded parts

In micro injection molding, the specific cavity surface texture and roughness directly influence the polymer flow and the heat transfer between polymer melt and mold. In this work, two different types of laser-induced periodic surface structures, linear and hexagonal, were generated, and their impact on the flow length in micro injection molding was evaluated. A complete investigation of the surface treatment effect on the polymer flow was carried out, comparing the performance of an untreated cavity surface with surfaces modified by LIPSS. The phenomenon was examined by localizing the weld lines created by the polymer flowing in two parallel channels having different surface treatments. Several cavity inserts were treated by varying the LIPSS process parameters to generate surfaces with different micro-and nanostructures directions and periodicity. Furthermore, the paper addresses the hydro-phobicity achieved on the micro molded surfaces replicated from mold inserts with different LIPSS-based surface topography. Mold surfaces with linear and hexagonal LIPSS and the respective molded parts were analyzed by optical profilometry and scanning electron microscopy to characterize the cavity surfaces replication and localize the weld lines on the micro injection molded parts

The InfraCyrus infrasound sensor

Infrasound sensors are used for a wide range of geophysical applications as the monitoring of volcanic eruptions, the detection of bolides and the recording of infrasounds generated by earthquakes. In 2006 we started the development of cheap infrasound sensors, based on commercial electret microphones. They have been characterized by comparing their response function with existing broadband infrasound sensors. These sensors, called InfraCyrus, have a good response between 1 and 10 Hz, making their application useful for various geophysical purposes. Currently, about a dozen of sensors are deployed in the Neapolitan area showing good performances in the recording of local and regional infrasonic transients

Multi-time delay, multi-point Linear Stochastic Estimation of a cavity shear layer velocity from wall-pressure measurements

Multi-time-delay Linear Stochastic Estimation (MTD-LSE) technique is thoroughly described, focusing on its fundamental properties and potentialities. In the multi-time-delay ap- proach, the estimate of the temporal evolution of the velocity at a given location in the flow field is obtained from multiple past samples of the unconditional sources. The technique is applied to estimate the velocity in a cavity shear layer flow, based on wall-pressure measurements from multiple sensor