Miracle-dz/UniFAR-FTUs huggingface dataset:
Radiation from seismic sources in cased and cemented boreholes

Far-field, stationary phase approximations are often used to study the radiation of P- and S-waves from seismic sources located in boreholes, usually with an assumption of low frequency and in application to uncased boreholes. These two assumptions allow explicit analytical results for the radiation patterns to be derived, as boundary condition equations can be solved analytically in fairly simple forms. Applying the same methodology to cased and cemented boreholes, however, is much more difficult because of the increased number of simultaneous boundary condition equations. I circumvent this difficulty by solving the boundary condition equations numerically using propagator matrices, as is generally done in the calculation of synthetic full-waveform acoustic logs. In this way, the assumption of low frequency is also avoided, and a generalized stationary-phase solution for sources in general, concentrically layered borehole models is easily obtained.Computation of the radiation patterns for cased and uncased boreholes in various formations shows that the amplitude reduction, because of the introduction of casing, is a function of both source type and of formation velocities. Axial stress sources are less affected by the casing than either radial stress or volume-injection sources, and as formation velocity decreases, the effect of the casing becomes more significant as the impedance contrast between steel and the formation becomes larger. The new generalized stationary-phase solution also shows that as frequency approaches 1000 Hz, the results obtained by low-frequency approximations for stress sources can be inaccurate and that the energy radiated from the source becomes more highly directed in the horizontal directions. The radiation pattern begins to change relatively rapidly as a function of frequency, so that the resulting observations from broad-band sources will show changes in waveforms that mimic the effects of attenuation. These changes occur because the length of the source becomes important as wavelength decreases, demonstrating the need to consider the influence of frequency, as well as casing and cement, on source radiation.
Alluvial facies evolution during the Palaeozoic greening of the continents: case studies, conceptual models and modern analogues

The Palaeozoic greening of the continents – the appearance and expansion of embryophytes (land plants) in terrestrial environments – was arguably the most fundamental Phanerozoic change to the Earth system. Thirteen case studies of Cambrian to Devonian fluvial deposits from North America and Europe are documented here to illustrate the evolution of fluvial style during this period. During the Cambro‐Ordovician, prior to the advent of terrestrial vegetation, fluvial systems laid down relatively coarse sands with little mud, resulting in self‐formed channels and an architecture dominated by broad sheets of trough cross‐beds (sheet‐braided style). Similar deposits formed across a wide range of latitudes, and passed basinward into sandy coastal deposits. From the mid Ordovician onwards, an increase in floodplain mudstone corresponds broadly with the appearance of embryophytes, which would have progressively enhanced upland weathering, mud production and floodplain storage of fines. During the Late Silurian, small heterolithic channel bodies with lateral‐accretion sets provide the first evidence of meandering channels, and floodplain mudstones contain more varied palaeosols, especially calcretes which appear abundantly for the first time. By the Early Devonian, channel deposits comprise sandstone lenses (channelled‐braided style), probably due to the increased bank strength and cohesion and reduced potential for sediment sorting imparted by sand‐mud mixtures. Muddy coastal deposits are prominent. By the Upper Devonian, fluvial deposits commonly contain fossil trees and large mainstem meandering channels with lateral‐accretion sets, indicating that rooted vegetation stabilized channels. The advent of stable floodplains with levées, crevasse splays and organic litter would have encouraged the diversification of terrestrial invertebrates, which left alluvial ichnological signatures from the Late Silurian onwards.
A late ultramafic suite in the Kap Edvard Holm layered gabbro complex, East Greenland

Abstract The Kap Edvard Holm Complex is an early Tertiary layered gabbro situated on the western side of the Kangerdlugssuaq fjord. Layered olivine gabbros in the Taco Point area are cut by several wehrlitic sill-like bodies which comprise a late ultramafic suite. An intrusive wehrlitic facies in the inner part of the bodies consists of olivine (+minor chrome-spinel) orthocumulate with clinopyroxene oikocrysts and interstitial plagioclase, kaersutite and phlogopite. A replacive facies which occurs in the marginal zones is texturally similar to the intrusive facies but contains no chromespinel and is more feldspathic, varying from a melanocratic olivine gabbro to a feldspathic wehrlite. It occurs where the sills wedge out laterally, in the lower contact zones where finger structures are widely developed, and in the upper contact zones where wehrlitic pipes feed melanocratic sheets, called parasol structures, which preferentially follow mafic layers in the host olivine gabbro. The wehrlites formed by the intrusion of hot, hydrous, ultrabasic magma into consolidated layered olivine gabbro. The replacive facies was formed by the volume for volume metasomatic replacement of olivine gabbro; dissolution of plagioclase was accompanied by crystallization of olivine. Some clinopyroxene was initially resorbed and later reprecipitated during this process. The relatively dense pore magma migrating upwards was restricted to pipes and spread out laterally when it encountered readily replaced mafic layers, while below the sills gabbro was replaced en masse and finger structures were formed. Similar late ultramafic suites occur in ophiolites, and their presence in the Kap Edvard Holm Complex supports suggestions that it acted as an ocean ridge type magma chamber during the initiation of early Tertiary sea floor spreading in the North Atlantic.
Glomalin‐related Soil Protein Response to Heating Temperature: A Laboratory Approach

Forest fires are a recurrent natural phenomenon in the Mediterranean basin. Fires can affect physical, chemical and biological soil properties. The effects on soil properties are closely controlled by fire severity, which is a consequence of temperatures reached and the length of residence of heat in the soil. In this study, the response of glomalin‐related soil protein (GRSP) − a glycoprotein produced by arbuscular mycorrhizal fungi − to heating temperature has been studied. Laboratory heating treatments were carried out at 180°C, 200°C, 250°C, 300°C, 400°C and 500°C in soil samples from eight different sites in SE Spain. The sites selected had mainly different soil characteristics. The results of heating on soil water repellency and soil organic carbon (SOC) were also included in the study. GRSP response to temperature was different between sites. Redundancy analyses divided sandy soils from the rest of soil types. Total content of aggregates, SOC and clay and sand content were the most significant properties explaining the response of GRSP to heating treatments. Results showed that GRSP was affected even at low temperature. SOC response to temperature was very similar between sites. Soil water repellency did not appear after heating in wettable soils and disappeared in water‐repellent ones at temperatures over 200°C. Our results indicate that GRSP could provide relevant information about fire severity. Copyright © 2015 John Wiley & Sons, Ltd.
Impact of future Arctic shipping on high‐latitude black carbon deposition

The retreat of Arctic sea ice has led to renewed calls to exploit Arctic shipping routes. The diversion of ship traffic through the Arctic will shorten shipping routes and possibly reduce global shipping emissions. However, deposition of black carbon (BC) aerosol emitted by additional Arctic ships could cause a reduction in the albedo of snow and ice, accelerating snowmelt and sea ice loss. Here we use recently compiled Arctic shipping emission inventories for 2004 and 2050 together with a global aerosol model to quantify the contribution of future Arctic shipping to high‐latitude BC deposition. Our results show that Arctic shipping in 2050 will contribute less than 1% to the total BC deposition north of 60°N due to the much greater relative contribution of BC transported from non‐shipping sources at lower latitudes. We suggest that regulation of the Arctic shipping industry will be an insufficient control on high‐latitude BC deposition.
Chemical and mineralogical analysis of individual mineral dust particles

Individual mineral dust particles collected in a dust storm over Israel were analyzed by a scanning electron microscopy and energy-dispersed system (SEM-EDS). The analysis shows that the particles were mostly aggregates of varying mineralogical composition rather than pure minerals. It is also shown that sulfur (not associated with gypsum) and, to a lesser extent, iron tended to reside on the particles' surface, while Ca, Mg, K, Al, and Si were all an integral part of the particles. The lack of NaCI and sulfuric acid aerosols in the sample indicates that the air mass did not interact with marine air or with clouds. This conclusion is further supported by back trajectory calculations. These findings suggest that the sulfur in the aerosols did not result from atmospheric processes but rather originated from processes in the source region. Black residue, surrounding some of the particles, suggests the possible existence of organic matter in the sample, probably originating from biological activity in the soil at the source of the particles. The method of individual particle analysis provides important information about the composition and morphology of the particles, information that otherwise cannot be obtained by bulk analysis methods.
UNDERSTANDING ECOLOGICAL INTERACTIONS TO IMPROVE MANAGEMENT OF BROMUS TECTORUM IN RANGELAND AND CROPLAND ECOSYSTEMS

Bromus tectorum L. (downy brome or cheatgrass) has been called the most dominant invasive plant species in the western United States. It is a barrier to restoration efforts in degraded lands and a serious weed problem for small grain growers. Investigating ecological interactions that play a mechanistic role in its success is a necessary step towards developing effective ecologically-based management strategies for B. tectorum. We investigated how biotic and abiotic factors impact interactions between B. tectorum and desired vegetation, with implications for restoration of lands dominated by B. tectorum and management of B. tectorum in small-grain cropping systems. Our research objectives were; 1) appraise the impact of relative size and soil nitrogen (N) availability on interactions between B. tectorum and Pseudoroegneria spicata (Pursh) A. Love (bluebunch wheatgrass), a species important in rangeland revegetation, and, 2) determine the impacts of Wheat streak mosaic virus (WSMV), resource availability, and neighborhood characteristics on B. tectorum performance in a winter wheat (Triticum aestivum L.) system. Objective 1 was carried out in a greenhouse experiment with two trials, following an addition series factorial design with four density treatments for each species, three P. spicata size cohort treatments, and two N treatments. Regression analysis indicated that giving P. spicata an initial size advantage over B. tectorum increased its ability to both suppress and avoid suppression by B. tectorum. We also observed that while N availability increased productivity of both species, it did not change their competitive relationship. Objective 2 was explored in two trials of a field experiment using a split-plot design with N availability assigned to main plots, WSMV inoculation assigned to subplots, B. tectorum proximity to the nearest wheat row as a predictor, and neighborhood characteristics as covariates. Regression analysis indicated that in low and high N environments (compared to the recommended N rate), distance from row influenced individual B. tectorum biomass only in disease-free environments, suggesting that healthy wheat suppressed B. tectorum that was closest to the row. Wheat inoculated with WSMV did not suppress B. tectorum. In an intermediate N environment, increased distance from row increased B. tectorum performance only with WSMV inoculation.
Bio-inspired anomaly target detection of multi-spectral remote sensing data

Aimed to the limitation of present anomaly detection algorism under clutter background for multi-spectral remote sensing data, especially for the situations of dense spread target and exist different attributive of background objects, a bio-inspired anomaly detection algorithm was proposed. Simulate the information processing and fusion mechanism of fly multi-apertures vision system, multi-level background model was proposed to analysis and describe feature of clutter background. Then the threshold value can be chose adaptively according to the level of background model. The proposed algorithm didn’t need the prior knowledge about anomaly, and avoids the choosing of the background widow size. A fusion mechanism was proposed to fuse the different detection results with different level background model. Simulation experiment validated the effectiveness of proposed method.
Using SAR images to delineate ocean oil slicks with a texture-classifying neural network algorithm (TCNNA)

Satellite-borne synthetic aperture radar (SAR) data are widely used for detection of hydrocarbon resources, pollution, and oil spills. These applications require recognition of particular spatial patterns in SAR data. We developed a texture-classifying neural network algorithm (TCNNA), which processes SAR data from a wide selection of beam modes, to extract these patterns from SAR imagery in a semisupervised procedure. Our approach uses a combination of edge-detection filters, descriptors of texture, collection information (e.g., beam mode), and environmental data, which are processed with a neural network. Examples of pattern extraction for detecting natural oil seeps in the Gulf of Mexico are provided. The TCNNA was successful at extracting targets and rapidly interpreting images collected under a wide range of environmental conditions. The results allowed us to evaluate the effects of different environmental conditions on the expressions of oil slicks detected by the SAR data. By processing hundreds of SAR images, we have also found that the optimum wind speed range to study surfactant films is from 3.5 to 7.0 m·s–1, and the best incidence angle range for surfactant detection in C-band is from 22° to 40°. Minor postprocessing supervision is required to check TCNNA output. Interpreted images produce binary arrays with imbedded georeference data that are easily stored and manipulated in geographic information system (GIS) data layers.
The climate influence on the mid‐depth Northeast Atlantic gyres viewed by cold‐water corals

The neodymium (Nd) isotopic composition (expressed in epsilon units, ɛNd) of reef framework‐forming cold‐water corals provides unique measures of water mass provenance and mixing within the Northeast Atlantic today and in the past. A reconstruction of near thermocline water ɛNd from cold‐water corals of the Gulf of Cádiz and Porcupine Seabight spanning over the past 300,000 years, now revealed that climate cooling during Marine Isotope Stages (MIS) 7.2 and MIS 8/9 led to a retraction of the mid‐depth Subpolar Gyre (mSPG) to the west. Conversely, Northern Hemisphere warming and increasing fresh water fluxes to the northwest (Labrador Sea) favor a stronger eastward extension of the mSPG blocking the northward flow of temperate Atlantic water as observed during the early MIS 1 and the early stage MIS 5.5. These changes are likely the result of large‐scale south‐north displacement of the westerlies similar to present‐day observations that the North Atlantic Oscillation (NAO) is linked with mid‐depth ocean circulation. Based on these observations, we hypothesize that further climate warming will also strengthen the mSPG leading to a salt and temperature decrease in the Northeast Atlantic whereas salinity and temperature will increase in the temperate Atlantic. However, the amplitude of such changes on North Atlantic overturning remains to be tested.
Multi-scale frequency and absorption attributes of seismic signals

Seismic absorption is sensitive to gas saturation, and this can lead to a number of observable features, such as low dominant frequency, absence of high frequencies and dimming of reflections. We obtain the time–frequency distribution of seismic signals at different scales based on wavelet decomposition and try to analyse the response of high-frequency sections for the characterization of hydrocarbon reservoirs. We present a case study using multi-scale (dominant) frequency and multi-scale absorption, and demonstrate that the method is effective in recognizing a deep tight-sandstone gas reservoir. By this study, we can draw the conclusion that multi-scale frequency and absorption attributes may indicate the gassy areas in reservoirs, and we have obtained many good applications in the Sichuan basin of China.
Hemiuriformes de peces marinos de la Bahía de Chamela, México, con la descripción de una nueva especie del género Hysterolecitha (Digenea: Hemiuridae: Lecithasterinae)

SE ESTABLECE EL REGISTRO DE LOS HEMIURIFORMES QUE PARASITAN A PECES MARIONOS DE LA BAHIA DE CHEMALA, JALISCO, A PARTIR DE UNA MUESTRA DE 1102 HOSPEDEROS QUE REPRESENTAN A 114 ESPECIES. SE REGISTRA A PARAHEMIURUS MERUS LINTON, 1910, LECITHOCHIRIUM MICROSTOMUN CHANDLER, 1935, MYOSACCIUM MERUS MONTGOMERY, 1957, OPISTHADENA DIMIDIA LINTON, 1910, LEURODERA PACIFICA MANTER, 1940, GONOCERCELLA PACIFICA MANTER, 1940, DINURUS LONGISINUS LOOSS, 1907, DINURUS SCOMBRI YAMAGUTI, 1934, ECTENERUS VIRGULUS, LINTON, 1910, HYSTEROLECITHA SONIAE SP. NOV., APONURUS LAGUNCULA LOOSS, 1907, SYNAPTOBOTHRIUM APHAREI (YAMAGUTI, 1970) N. COMB. , LARVAS DE LA SUBFAMILIA DIDYMOZOINAE, HIRUDINELLA VENTRICOSA PALLAS, 1777 Y PROSORCHIOPSIS LEGENDREI DOLLFUS, 1947. HYSTELOLECITHA SONIAE SP. NOV. SE DIFERENCIA DE LOS DEMAS MIEMBROS DEL GENERO POR PRESENTAR UNA VESICULA SEMINAL GLOBOSA, UNA VESICULA PROSTATICA QUE SE CONECTA CON EL SACO GENITAL A TRAVES DE UN CONDUCTO LARGO Y SINUOSO Y UN SACO GENITAL MUSCULOSO BIEN DESARROLLADO, CON UNA VESICULA HEMAFRODITA BIPARTIDA EN SU INTERIOR. SE POSTULA A LA GRAN CAPACIDAD DE COLONIZACION DEL GRUPO COMO RESPONSABLE DE LOS PATRONES DE DISTRIBUCION GEOGRAFICA Y HOSPEDATORIA DE LAS ESPECIES Y SE SENALA LA NECESIDAD DE REALIZAR REVISIONES A NIVEL GENERICO , LAS QUE, AUNADAS CON ANALISIS FILOGENETICOS, PERMITAN CONSTRUIR UNA CLASIFICACION NATURAL DEL GRUPO.
Isotope fractionation by sulfate-reducing natural populations and the isotopic composition of sulfide in marine sediments

Isotope fractionations during sulfate reduction by natural bacterial populations were measured in seven different marine sediments and compared with the isotopic composition of solid-phase sulfides in the same sediments. The measured fractionations during sulfate reduction could explain only between 41% and 85% of the 34S depletion in the sedimentary sulfides. This result directly demonstrates that the depletion of 34S in solid sulfides is an expression of the combined activity of sulfate-reducing organisms with additional fractionations accumulated during the oxidative part of the sulfur cycle. The only known process to significantly augment the fractionations created during sulfate reduction is the microbial disproportionation of the intermediate sulfur compounds: elemental sulfur, thiosulfate, and sulfite. In a simple model, we show how important each of these disproportionation processes could be in generating the isotopic composition of sedimentary sulfides. The sulfate reduction rates in the sediments studied varied by a factor of 1000 and did not correlate with the fractionation during sulfate reduction. By contrast, a correlation was observed between sulfate- reduction rate and the extent of 34S depletion into sedimentary sulfides, the most 34S-depleted sulfides found in sediments supporting the lowest rates of sulfate reduction. Thus, the fractionations imposed during the disproportionating processes are better expressed in sediments with low sulfate-reduction rates. The direct phototrophic oxidation of sulfide to sulfate, with minimal fractionation, may have been important in the sediments that had a high sulfate-reduction rate.
PALEOVENTOS E PALEOCORRENTES SUBAQUOSAS DO SISTEMA DEPOSICIONAL PIRAMBÓIA NOS ESTADOS DE SÃO PAULO E PARANÁ, BACIA DO PARANÁ: ESTUDO BASEADO EM ANÁLISE ESTATÍSTICA DE DADOS AZIMUTAIS

Cross stratification dip directions data distributed along the outcrop area of the Piramboia eolian depositional system (Permian and/Triassic of Parana Basin), in the states of Sao Paulo and Parana, South Brazil, were grouped according to stratigraphic interval, geographic position and depositional facies criteria. Paleowinds and subaquous paleocurrents directions were estimated from eolian and subaqueous (coastal and/or fluvial) facies data, through statistical analysis. The geographic distribution of these paleocurrents and paleowinds directions, during the development of the Piramboia system, is discussed in terms of provenance and paleogeography, including aspects of atmospheric circulation and relief. The paleowind pattern shows a convergence zone, in the State of Parana, characterized by eolian influx from NW and NE, in the northern area, and from SW, in the southern area. During the development of Piramboia depositional system, this zone migrates from the central to the south-central portion of the Parana State. About the subaqueous facies for the lower Piramboia depositional system, the paleocurrents exhibit provenance from NE in the southwest of Sao Paulo State and north of Parana State. Bidirectional paleocurrents (NNE-SSW) are observed in the central-eastern area of Sao Paulo State. For the upper Piramboia depositional system, the paleocurrents found are from SE in the northern Sao Paulo State, and from NE and NNE in the central and southern areas of Parana State. Paleocurrents with high dispersion, without a main dip direction, were observed in the central-eastern portion of Sao Paulo and northern Parana. The observed paleowind pattern reflects air mass convergence, in global or regional scale of atmospheric circulation. In the regional scale, this convergence would be related to blockade exerted by a geographic barrier in Parana, which acted as an obstacle to the southern winds, in its north flank, and to the northern winds, in its southern flanks. The coincidence between the zone with reversal of paleowinds and subaquous paleocurrents and the area with concentration of rudaceous facies und with thinning of the stratigraphic unit are suggestive of the existence of structural highs internally to the basin during the development of the Piramboia depositional system.
An algorithm for multiple fault diagnosis in analogue circuits

The paper deals with multiple fault diagnosis of analogue AC or DC circuits with limited accessible terminals for excitation and measurement and brings an algorithm for identificating faulty elements and evaluating their parameters. The main achievement is a method enabling us to efficiently identify faulty elements. For this purpose some testing equations are derived playing a key role in identification of possibly faulty elements which are next verified using a test of acceptance. The proposed approach is described in detail for double fault diagnosis. Also extension to triple fault diagnosis is given. Although the method pertains to linear circuits, some aspects of multiple fault diagnosis of non‐linear circuits can be also performed using the small signal approach. Two numerical examples illustrate the proposed method and show its efficiency. Copyright © 2006 John Wiley & Sons, Ltd.