Fast Computation of Voigt Functions via Fourier Transforms

This work presents a method of computing Voigt functions and their derivatives, to high accuracy, on a uniform grid. It is based on an adaptation of Fourier-transform based convolution. The relative error of the result decreases as the fourth power of the computational effort. Because of its use of highly vectorizable operations for its core, it can be implemented very efficiently in scripting language environments which provide fast vector libraries. The availability of the derivatives makes it suitable as a function generator for non-linear fitting procedures.Comment: 8 pages, 1 figur

Breeding waterbird use of rice fields in southwestern Louisiana

Rice fields are agricultural wetlands concentrated in several areas in the U.S., including southwestern Louisiana. Rice fields are flooded for much of the year and support thick emergent vegetation, potentially providing high-quality habitat for several species of breeding waterbirds. The objectives of this study were to (1) determine relative nest density, nest success, and habitat associations of breeding waterbirds in southwestern Louisiana rice fields and (2) determine the effectiveness of callback surveys as a monitoring tool. In the summers of 2004 and 2005, marsh bird surveys and nest searches were conducted in Cameron, Jefferson Davis, Vermilion, and Acadia Parishes in southwestern Louisiana. In 2004, 42 fields were searched and 30 of those were surveyed. In 2005, 40 fields were searched and 60 were surveyed. Purple gallinules nested in the highest densities in both years, followed by fulvous whistling-ducks, king rails, common moorhens, and least bitterns. A total of 283 purple gallinule nests, 176 fulvous whistling-duck nests, 77 king rail nests, 59 common moorhen nests, and 12 least bittern nests were found. The highest nest densities for purple gallinules and king rails were in fields with a high proportion of irrigation canals around the perimeters and a low proportion of trees. High relative nest density for purple gallinules was also associated with a high proportion of rice fields within 1 km of each field. Fulvous whistling-ducks responded the least to the local and landscape characteristics, but were associated with a high proportion of soybean fields near rice fields. Birds began nesting at the beginning of June and most nests were terminated by the time of harvest. Nest survival, or the percentage of nests to hatch at least one egg, was between 52% and 79% for purple gallinules, ~50% for king rails, and ~40% for fulvous whistling-ducks. Most survey responses were detected in June, and survey detections were concentrated in similar areas as the highest nest densities. Callback surveys were an effective technique for monitoring secretive marsh birds in this region

Geologically constrained joint inversion of hydraulic, tracer and ERT data for process visualization

Seawater intrusion (SWI) consists in the movement of seawater (SW) into freshwater (FW) aquifers, contaminating drinking water resources. SWI, along with the parallel reduction of Submarine Groundwater Discharge may lead to ecological impacts beyond the reduction of FW resources. Water salinity is the critical physical property to identify SWI. The salinity contrast between FW (~1g/L) and SW (35g/L) is high enough for salinity and, therefore, water electrical conductivity (ECw), to be indirectly measured using geophysical techniques such as geophysical logs (e.g. induction) or electrical and electromagnetic methods (e.g. electrical resistivity tomography, ERT). Although the context of SWI sounds ideal for the use of geophysics, ERT displays poor resolution in depth. We propose using cross-hole ERT (CHERT) to enhance resolution, placing the electrodes in depth along the boreholes. We tested it for the first time in a SWI context, at the Argentona experimental site, some 40 km NE of Barcelona. Results of the 2-years time-lapse CHERT monitoring showed that the use of CHERT and surface ERT increased the model resolution, and the bulk EC (ECb) values from CHERT were validated with induction logs from the site. We were able to image the seasonal fluctuations of groundwater flux that cause the SW-FW interface to move seawards during periods of high flux or landwards during periods of low flux; as well as the salinization of the aquifer due to an intense drought in the study area during the monitoring period. Two short-term events were also imaged: a decrease in ECb related to a heavy rain event, and an increase in ECb in the beach area related to storm surges. We built a hydrogeophysical model to characterize the Argentona site using all available data types. The model couples a density-dependent flow and transport simulator with a geoelectrical solver through a petrophysical relation. This model was calibrated by minimizing the misfit between observed and simulated hydraulic heads, salt concentrations and apparent ECb. The calibration was done on four time stages: a pseudo steady-state period, a model warm-up period for the introduction of time-varying boundary conditions, a calibration period covering the first year of the Argentona site monitoring, and a validation period covering the second year. The latter was used to assess the prediction capability of the models. The procedure allowed us to update the original conceptual model and demonstrate the importance of even the finest silt-rich layers. Then, three inverse problems were performed on the updated conceptual model: a) using the traditional point measurements of heads and salinity; b) adding the time variations of heads and the spatial differences of salinity to address common issues of using heads and salinity measurements taken from boreholes in coastal aquifers; and c) adding the apparent ECb from the time-lapse CHERT. We discuss the value of using time variations of heads, instead of only head absolute values; as well as on the use of spatial differences of salt concentrations. The model calibrated using all types of data (heads, salinity and ECb) had the best prediction capability and the model was able to reproduce the main events observed during the two years of monitoring of the Argentona site. Numerical dispersion prevents the model from simulating FW (0-1 g/L), which affects calibration. To tackle this issue, we propose to use an alternative conversion from water salinity to ECw that corrects for numerical dispersion when computing ECb. The methodology consists in applying and calibrating the error function to reduce salinity in the FW zone, and increase it in the SW zone. The error function calibration can also change the width of the FW-SW interface. This conversion improved the model prediction capability and led to a set of parameters less affected by numerical dispersion (e.g. estimated petrophysical parameters are within the expected range).La intrusión salina (SW) es el flujo de agua de mar (SW) hacia acuíferos de agua dulce (FW), contaminando las reservas de agua potable. La SWI, más la disminución de la Descarga de Agua Submarina, tiene impactos ecológicos más allá de la reducción del agua potable. La salinidad del agua es clave para identificar la SWI. El contraste entre el FW (~1g/L) y el SW (35g/L) es tan alto que la salinidad, y la conductividad eléctrica del agua (ECw), puede ser medida usando técnicas geofísicas como los sondeos (e.g. inducción) o los métodos eléctricos y electromagnéticos (e.g. tomografía de resistividad eléctrica, ERT). Aunque el contexto de la SWI suene ideal para el uso de la geofísica, la ERT tiene baja resolución en profundidad. Proponemos el uso de ERT entre pozos (CHERT) para mejorar la resolución, con los electrodos a lo largo de los piezómetros. Se ha testeado el CHERT por primera vez para la SWI en el sitio experimental de Argentona, a 40 km al noreste de Barcelona. Los resultados de los dos años de monitoreo muestran que el uso del CHERT y del ERT mejora la resolución del modelo, y los valores de la EC del medio (ECb) se validaron con los sondeos de inducción. Se logró visualizar las fluctuaciones temporales de los flujos de agua subterránea que causan que la interfaz FW-SW se mueva hacia el mar en periodos de alto flujo, o hacia el interior en periodos de bajo flujo; al igual que la salinización del acuífero debido a una sequía intensa en el área durante el periodo de monitoreo. Dos eventos de corta duración también se detectaron: una disminución en la ECb por un evento de lluvia intensa, y un aumento de la ECb en el área de la playa por las mareas de tormenta. Se construyó un modelo hidrogeofísico para caracterizar el sitio de Argentona usando todos los datos disponibles. El modelo acopla dos simuladores a través de una relación petrofísica: el de flujo y transporte con densidad variable y el de geoeléctrica. El modelo se calibró minimizando la distancia entre las medidas y las simulaciones de los niveles, las salinidades y las ECb aparentes. La calibración se hizo en cuatro periodos: uno pseudo-estacionario, uno de calentamiento que introduce las series temporales, uno de calibración que cubre el primer año de monitoreo, y uno de validación que cubre el segundo año. Este último fue usado para evaluar la capacidad de predicción de los modelos. El procedimiento nos permitió actualizar el modelo conceptual y demostrar la importancia de las capas de limo más finas. Luego, se resolvieron tres problemas inversos usando el modelo conceptual actualizado: a) usando las medidas tradicionales de niveles y de salinidad; b) añadiendo las variaciones temporales de nivel y la variación espacial de salinidad para hacer frente a la dificultad de usar los datos de nivel y salinidad tomados de pozos en acuíferos costeros; y c) añadiendo la ECb aparente del CHERT. Discutimos sobre el valor añadido de usar las variaciones temporales de nivel, en vez de únicamente los valores absolutos; así como sobre el uso de las diferencias espaciales de salinidad. El modelo calibrado usando todos los datos (niveles, salinidad y ECb) tuvo la mejor capacidad de predicción y es capaz de reproducir los principales eventos observados durante los dos años de monitoreo en el sitio de Argentona. La dispersión numérica evita que el modelo simule la zona de FW (0-1 g/L), afectando la calibración. Para esto, proponemos una conversión alternativa entre la salinidad y la ECw que corrige la dispersión numérica al calcular la ECb. El método consiste en aplicar y calibrar la función de error para reducir la salinidad del agua en la zona de FW, e incrementarla en la zona de SW. Esta calibración también puede cambiar el ancho de la interface FW-SW. La conversión mejoró la capacidad de predicción del modelo y llevó a obtener un conjunto de parámetros menos afectado por la dispersión numérica (e.g. parámetros petrofísicos estimados dentro del rango de valores esperados).Postprint (published version

Reduced Noise Gas Turbine Engine System and Supersonic Exhaust Nozzle System Using Elector to Entrain Ambient Air

One embodiment of the present invention is a unique gas turbine engine system. Another embodiment is a unique exhaust nozzle system for a gas turbine engine. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for gas turbine engine systems and exhaust nozzle systems for gas turbine engines. Further embodiments, forms, features, aspects, benefits, and advantages of the present application will become apparent from the description and figures provided herewith

The genesis of the concept of group presentation as seen in papers of Cayley, Kronecker and Dyck

Call number: LD2668 .T4 MATH 1988 R63Master of ScienceMathematic

Time-lapse cross-hole electrical resistivity tomography (CHERT) for monitoring seawater intrusion dynamics in a Mediterranean aquifer

Surface electrical resistivity tomography (ERT) is a widely used tool to study seawater intrusion (SWI). It is noninvasive and offers a high spatial coverage at a low cost, but its imaging capabilities are strongly affected by decreasing resolution with depth. We conjecture that the use of CHERT (cross-hole ERT) can partly overcome these resolution limitations since the electrodes are placed at depth, which implies that the model resolution does not decrease at the depths of interest. The objective of this study is to test the CHERT for imaging the SWI and monitoring its dynamics at the Argentona site, a well-instrumented field site of a coastal alluvial aquifer located 40¿km NE of Barcelona. To do so, we installed permanent electrodes around boreholes attached to the PVC pipes to perform time-lapse monitoring of the SWI on a transect perpendicular to the coastline. After 2 years of monitoring, we observe variability of SWI at different timescales: (1) natural seasonal variations and aquifer salinization that we attribute to long-term drought and (2) short-term fluctuations due to sea storms or flooding in the nearby stream during heavy rain events. The spatial imaging of bulk electrical conductivity allows us to explain non-monotonic salinity profiles in open boreholes (step-wise profiles really reflect the presence of freshwater at depth). By comparing CHERT results with traditional in situ measurements such as electrical conductivity of water samples and bulk electrical conductivity from induction logs, we conclude that CHERT is a reliable and cost-effective imaging tool for monitoring SWI dynamics.This work was funded by the project CGL2016-77122-C2-1-R/2-R of the Spanish Government. This project also received funding from the European Commission, Horizon 2020 research and innovation programme (Marie Sklodowska-Curie (grant no. 722028)). The author Albert Folch is a Serra Húnter Fellow.Peer ReviewedPostprint (published version

Oxide_Oxide Ceramic Matrix Composite (CMC) Exhaust Mixer Development in the NASA Environmentally Responsible Aviation (ERA) Project

LibertyWorks, a subsidiary of Rolls-Royce Corporation, first studied CMC (ceramic matrix composite) exhaust mixers for potential weight benefits in 2008. Oxide CMC potentially offered weight reduction, higher temperature capability, and the ability to fabricate complex-shapes for increased mixing and noise suppression. In 2010, NASA was pursuing the reduction of NOx emissions, fuel burn, and noise from turbine engines in Phase I of the Environmentally Responsible Aviation (ERA) Project (within the Integrated Systems Research Program). ERA subtasks, including those focused on CMC components, were being formulated with the goal of maturing technology from Proof of Concept Validation (Technology Readiness Level 3 (TRL 3)) to System/Subsystem or Prototype Demonstration in a Relevant Environment (TRL 6). LibertyWorks, a subsidiary of Rolls-Royce Corporation, first studied CMC (ceramic matrix composite) exhaust mixers for potential weight benefits in 2008. Oxide CMC potentially offered weight reduction, higher temperature capability, and the ability to fabricate complex-shapes for increased mixing and noise suppression. In 2010, NASA was pursuing the reduction of NOx emissions, fuel burn, and noise from turbine engines in Phase I of the Environmentally Responsible Aviation (ERA) Project (within the Integrated Systems Research Program). ERA subtasks, including those focused on CMC components, were being formulated with the goal of maturing technology from Proof of Concept Validation (Technology Readiness Level 3 (TRL 3)) to System/Subsystem or Prototype Demonstration in a Relevant Environment (TRL 6). Oxide CMC component at both room and elevated temperatures. A TRL5 (Component Validation in a Relevant Environment) was attained and the CMC mixer was cleared for ground testing on a Rolls-Royce AE3007 engine for performance evaluation to achieve TRL 6

RGS12 Interacts with the SNARE-binding Region of the Ca v 2.2 Calcium Channel

Activation of GABAB receptors in chick dorsal root ganglion (DRG) neurons inhibits the Cav2.2 calcium channel in both a voltage-dependent and voltage-independent manner. The voltage-independent inhibition requires activation of a tyrosine kinase that phosphorylates the alpha1 subunit of the channel and thereby recruits RGS12, a member of the "regulator of G protein signaling" (RGS) proteins. Here we report that RGS12 binds to the SNARE-binding or "synprint" region (amino acids 726-985) in loop II-III of the calcium channel alpha1 subunit. A recombinant protein encompassing the N-terminal PTB domain of RGS12 binds to the synprint region in protein overlay and surface plasmon resonance binding assays; this interaction is dependent on tyrosine phosphorylation and yet is within a sequence that differs from the canonical NPXY motif targeted by other PTB domains. In electrophysiological experiments, microinjection of DRG neurons with synprint-derived peptides containing the tyrosine residue Tyr-804 altered the rate of desensitization of neurotransmitter-mediated inhibition of the Cav2.2 calcium channel, whereas peptides centered about a second tyrosine residue, Tyr-815, were without effect. RGS12 from a DRG neuron lysate was precipitated using synprint peptides containing phosphorylated Tyr-804. The high degree of conservation of Tyr-804 in the SNARE-binding region of Cav2.1 and Cav2.2 calcium channels suggests that this region, in addition to the binding of SNARE proteins, is also important for determining the time course of the modulation of calcium current via tyrosine phosphorylation