Miracle-dz/UniFAR-FTUs huggingface dataset:
About an inverse electromagnetic coefficient problem: uniqueness with partial boundary data and quasi-reversibility method for data completion

This paper deals with two questions relative to the inverse coefficient problem of recovering the electric permittivity and conductivity of a medium from partial boundary data at a fixed frequency. The underlying model is the time-harmonic Maxwell equations in the electric field. First, an identifiability result is proved for partial boundary data without restrictive conditions on the inaccessible part of the boundary. The second issue that is addressed, is the data completion problem on the inaccessible part of the boundary. The quasi-reversibility method is studied, and different mixed formulations are proposed. Well-posedness and convergence results are proved. Various two- and three dimensional numerical simulations attest the efficiency of the method, in particular for noisy data.
Gas exchange rates for a first‐order stream determined with deliberate and natural tracers

Gas transfer velocities have been determined for a first-order stream by performing a 3-hour release of the volatile tracer sulfur hexafluoride, SF{sub 6}, and the nonvolatile tracer tritiated water, {sup 3}H{sub 2}O. The average gas transfer velocity for the 292-m reach was 29 cm/h which corresponds to a reaction coefficient for oxygen at 25C of 134 day{sup {minus}1}. Groundwater inflow along the stream was corrected for by measuring the downstream dilution of the {sup 3}H{sub 2}O spike. Downstream discharge increased from 0.5 L/s, 2 m downstream of the point of tracer release, to 19.3 L/s at a point 292 m downstream. As an alternative to using (radioactive) {sup 3}H{sub 2}O, the authors investigated the possibility of using natural radon, {sup 222}Rn, as a groundwater tag and using the variation of SF{sub 6} and {sup 222}Rn along the stream to determine gas exchange rates and groundwater inflow. The method yielded an average transfer velocity of 21 cm/h and underestimated the groundwater inflow by a factor of 3. This large discrepancy is attributed to a doubling of stream discharge between the time the stream was sampled for radon and the tracer experiment and the limited number of radon samples.
Offshore transport of the Alaska Coastal Current water induced by a cyclonic wind field

The Alaska Coastal Current (ACC) is driven by multiple sources of coastal freshwater discharge and propagates alongshore over hundreds of kilometers. The ACC is also subject to downwelling‐favorable winds associated with cyclonic wind systems. Spatially‐uniform, downwelling winds trap the buoyant ACC waters nearshore. However, we demonstrate with numerical experiments that spatial wind variations, due either to a stationary or translating cyclone, can enhance the offshore transport of buoyant coastal waters in comparison to no‐wind conditions. A stationary atmospheric cyclone induces a strong convergence in the coastal current at the upstream periphery of the cyclone. This convergence generates an offshore filament of buoyant water, which evolves into detached anticyclone. A transient atmospheric cyclone enhances the offshore spreading of freshwater by intensifying mesoscale variability of the coastal current. Thus, the spatial structure of the wind field represents a potentially important mechanism for cross‐shelf freshwater transport.
The hexagonal discrete global grid system appropriate for remote sensing spatial data

With the enrichment of earth observing measures, the interesting field of photogrammetry and remote sensing monitoring has expanded gradually to the whole world, traditional planar data structure no longer satisfies the globaloriented application of geo-spatial data. Breaking through the constraints of planes, managing and utilizing remote sensing spatial data in the real earth mode have now become an inevitable trend. Discrete Global Grid System (DGGS) provides new ideas for the constructing of new spatial data models. Based on the frame of DGGS, this paper designs a new hexagonal hierarchical structure of remote sensing data that has the attribute of geographical location. Compared with the traditional image rectangular quadtree structure, this structure is more applicable to the management and arrangement of global spatial data (especially the raster data) and can express and process multi-resolution global geospatial data seamlessly.
Accuracy of travel time distribution (TTD) models as affected by TTD complexity, observation errors, and model and tracer selection

Analytical models of the travel time distribution (TTD) from a source area to a sample location are often used to estimate groundwater ages and solute concentration trends. The accuracies of these models are not well known for geologically complex aquifers. In this study, synthetic data sets were used to quantify the accuracy of four analytical TTD models as affected by TTD complexity, observation errors, model selection, and tracer selection. Synthetic TTDs and tracer data were generated from existing numerical models with complex hydrofacies distributions for 1 public‐supply well and 14 monitoring wells in the Central Valley, California. Analytical TTD models were calibrated to synthetic tracer data, and prediction errors were determined for estimates of TTDs and conservative tracer ( NO3− ) concentrations. Analytical models included a new, scale‐dependent dispersivity model (SDM) for two‐dimensional transport from the water table to a well and three other established analytical models. The relative influence of the error sources (TTD complexity, observation error, model selection, and tracer selection) depended on the type of prediction. Geological complexity gave rise to complex TTDs in monitoring wells that strongly affected errors of the estimated TTDs. However, prediction errors for NO3− and median age depended more on tracer concentration errors. The SDM tended to give the most accurate estimates of the vertical velocity and other predictions, although TTD model selection had minor effects overall. Adding tracers improved predictions if the new tracers had different input histories. Studies using TTD models should focus on the factors that most strongly affect the desired predictions.
U-Pb Isotopic evidence for the accretion of a continental microplate in the Zalm region of the Saudi Arabian Shield

The area covered by this work includes three of the main tectonic units of the Arabian Shield: the Afif continental terrain, the Nabitah suture with its associated mobile belt, and the Asir ensimatic arc terrain. The geology of the Zalm area is well understood, and this geochronologic and isotopic study confirms that the southern Afif terrain was a continental microplate in the late Proterozoic. The study also provides a time frame for the crustal evolution of this part of the Shield. The Kabid formation is the oldest in the region and comprises pelitic, arkosic and felsic high-grade paragneisses. U-Pb zircon data from a pelitic garnet-sillimanite gneiss show that this part of the continental basement in the southern Afif terrain may be as old as 1770 Ma. Isotopic nalyses indicate that lead from the Kabid gneiss resided in the upper continental crust for a long period before 1770 Ma, and consequently Archaean source rocks may be present within the southern Afif terrain. Pb and Rb-Sr isotopic data in the Zalm region reveal a change in the nature of the underlying crust, from continental basement in the northeast, to less radiogenic marginal arc rocks in the southwest. This change is coincident with both aeromagnetic data, and a facies change within a pre-collision marginal basin. Miogeosynclinal continental shelf facies of the Siham group lie unconformably over the Kabid formation, and are in the area of continental lead signatures. Eugeosynclinal deep water sediments and volcanics, in association with ultramafic rocks, occur in the area of marginal arc signatures. U-Pb zircon age determinations show that this 'Andean' continental margin developed before about 720 Ma, and emplacement of calc-alkaline plutonic rocks continued until about 690 Ma. During the period 685-640 Ma, the continental Afif microplate collided with the Asir terrain as part of the Nabitah orogeny. At approximately 640 Ma ago, the Najd strike-slip faulting commenced with a dextral phase that controlled the emplacement of granitic plutons as well as the development of a series of large pull-apart grabens. Some of these grabens were floored by new oceanic crust and were filled with volcanosedimentary rocks of the Bani Ghayy group. Subsequently, the Najd fault system changed to sinistral strike-slip motion at about 620 Ma ago.
Recent advances and applications in complex resistivity measurements

Several years of accumulating complex resistivity spectral measurements have indicated that there are still many unexplored areas in induced polarization surveying that need to be investigated for a more complete understanding of the polarization process. In addition to providing mineral discrimination capabilities, complex resistivity spectra can be used to differentiate between various barren host rock responses, to facilitate the complete removal of electromagnetic coupling, and to identify pipeline, fence, and various other cultural coupling effects. Results of field measurements are presented in an effort to demonstrate the utility of and necessity for making complete spectral measurements for serious geophysical interpretation. Correlation of field measurements with laboratory measurements on core samples from the same area demonstrates that strong electromagnetic coupling can be accurately removed from complete spectra without removing the important rock response. Recent field and laboratory measur.
Influence of Wind Stress, Wind Stress Curl, and Bottom Friction on the Transport of a Model Antarctic Circumpolar Current

AbstractEddy-permitting simulations of a wind-driven quasigeostrophic model in an idealized Southern Ocean setting are used to attempt to describe what sets the wind-driven circumpolar transport of the Antarctic Circumpolar Current (ACC). For weak forcing, the transport is well described as a linear sum of channel and basin components. The authors’ main focus is on stronger forcing. In this regime, an eddy-driven recirculation appears in the abyssal layer, and all time-mean circumpolar streamlines are found to stem from a Sverdrup-like interior. The Sverdrup flux into Drake Passage latitudes can then be thought of as the sum of one part that feeds the circumpolar current and another that is associated with the recirculation. The relative fractions of this partitioning depend on the bottom drag, the midchannel wind stress, and the wind stress curl. Increasing the strength of the bottom drag reduces the recirculation and increases circumpolar transport. Increasing a zero-curl eastward wind stress reduces th.
Overlapping rift zones at the 5.5°S offset of the East Pacific Rise

A Seabeam and magnetometer survey of the Pacific-Nazca plate boundary around 5.5°S mapped a “nontransform offset” whose geology and kinematics seem typical of a whole class of structures formed where fast-spreading rises are laterally offset for distances less than the width of a subaxial magma chamber. Though the spreading center is abruptly displaced by 15 km right laterally, there is no trace of strike-slip faulting. Instead the ends of two 100 km-long axial volcanic ridges veer 15° toward each other and overlap for more than 20 km. In this overlapping region, between 5°22′S and 5°32′S, accretion of the upper oceanic crust by dike injection and eruption is partitioned between two adjacent and parallel rift zones with oblique and one-sided spreading. A continuous but dog-legged magma chamber is inferred to underlie both rift zones and an intervening 9-km wide volcano-studded basin. A strong magnetic signature from the crust, which accreted around this oblique chamber identifies the trace of the offset on the adjacent rise flank; in the past 0.5×106 years the southern axial ridge has propagated north at 40 mm/yr, 55% of the spreading half-rate.
The Discovery of an Early Bearing-Dial – Further Investigations

The first part of the above title was used in the Journal in 1953 for a paper by Captain Carl V. Solver. His special interest was to discover how the Norse navigators of the Viking age found their way across the North Atlantic. He was the first person to interpret the small wooden disc shown in Fig. i as a fragment of an early bearing-dial and investigations since his paper was published provide considerable supportive evidence. At the time, there was some strong opposition to his views, but he persisted with his theory and wrote a book, Vestervejen. This formed a basis for other researchers to carry his work further and, as a result, there have been many international contributions over some 40 years. The archaeological find from southern Greenland seems to show that the Norse navigator used the path of the Sun's shadow during the day as the basis of a compass.
Examining Environmental Injustice in Florida

This project analyzes potential areas of environmental injustice on a census tract level throughout Florida. Data on race and median household income were compiled into ArcGIS 10.2. 2 along with Toxic Release Inventory (TRI) locations to determine if communities with low income or large minority population are disproportionately exposed to sources of heavy pollution. Statistical tests found that high minority and low income census tracts were more likely to be within two miles of a TRI site and that census tracts containing two or more TRI sites had significantly lower median household incomes than census tracts with only one or fewer TRI sites. An examination of Gadsen county revealed that several high-minority population census tracts disproportionately contain or are located near TRI sites. Additional studies examining water and air quality, as well as examining exposure to hazardous chemicals from superfund sites or underwater storage tanks would be beneficial for the assessment of environmental injustice in Florida.
Short Paper: Time of docking of the Connemara terrane with the Delaney Dome Formation, western Ireland

The Connemara Dalradian terrane was emplaced over the Delaney Dome Formation from the NNW by near orthogonal movement on the Mannin Thrust, a linkage that has survived later movement. Rb-Sr isotopic analyses of micas and whole rocks from the Delaney Dome mylonites constrain the age of movement on the thrust to 447 ±4Ma. This time of thrusting correlates with much other tectonic activity in the Caledonides and may represent a time of ‘docking’ of the Midland Valley block with the more northerly terranes.
A TEMPORAL EXTENSION TO TRADITIONAL EMPIRICAL ORTHOGONAL FUNCTION ANALYSIS

This paper describes the application of temporal maximum autocorrelation factor analysis to global monthly mean values of 1996-1997 sea surface temperature (SST) and sea surface height (SSH) data. This type of analysis can be considered as an extension of traditional empirical orthogonal function (EOF) analysis, which provides a non-temporal analysis of one variable over time. The temporal extension proves its strength in separating the signals at different periods in an analysis of relevant oceanographic properties related to one of the largest El Nino events ever recorded.
Time variations of aftershock decay parameters of the 2009 April 6 L’Aquila (central Italy) earthquake: evidence of the emergence of a negative exponential regime superimposed to the power law

SUMMARY We analysed the time evolution of the decay parameters of the L’Aquila aftershock sequence, neglecting spatial variability. During the first two months after the main shock, the sequence showed quite unusual properties: a particularly slow decay of the aftershock rate that progressively accelerated and a very scarce sensitivity to the occurrence of strong aftershocks. In the first few days, the decrease of the aftershock rate was compatible with an Omori's process with power-law exponent p ≈ 0.5. The successive increase of the exponent up to about p = 1.2 in the following months can be interpreted as the emergence of a negative exponential regime that has been found to control the decay of other sequences occurred in Italy and California. In fact, two decay models, even including a negative exponential term, reproduce the aftershock rate in the first 60 days significantly better than the Omori's law according to the Akaike information criteria. In this time interval, the strongest aftershocks do not seem to have produced significant increases of the aftershock rate while a couple of them seem to be preceded, rather than followed, by a slight increase of the rate. Consequently, epidemic models do not perform significantly better than non-epidemic ones for durations shorter than 60–80 days. A slow change of decay parameters seems to have been preceded a clear increase of the rate occurred 80 days after the main shock in correspondence of a relatively strong aftershock in the main fault area and of the activation of a previously silent fault segment in the NW. As a consequence of such reactivation, epidemic models become preferable with respect to non-epidemic ones for longer durations. The L’Aquila main shock productivity is the highest ever observed in Italy since the installation of a modern seismic network in Italy in mid 1980s, as the number of generated aftershock is from three to 10 times higher than for any previous earthquake of similar magnitude.
Statistical Approaches to Estimate the Recurrence of Earthquakes in the Eastern Mediterranean Region

Risk analyses made in an area of seismic activity are going to be of great importance in determining earthquake occurence intervals and recurrence periods. Several methods, some of which include statistical methods, have been developed for this purpose. Gamma, Weibull distributions and Markov, Poisson, Gumbel are the most frequently used methods in this regard. In this study, instrumental records of 165 earthquakes of Ms ≥ 4 which occured in Eastern Mediterranean Region (Cukurova, Turkey) were investigated. These earthquake records were obtained from the Turkish Earthquake Research Department (ERD). To explain the seismic activity of the area, the relationship between magnitude and frequency was explained by using earthquake distribution in time. The magnitude-frequency relationship of the study area was calculated by means of the "Log N= 6.29 - 0.96 M" equation. Occurrence probability and recurrence periods of the earthquakes were computed by utilizing Poisson, Gumbell and Exponential Distribution Models and the results were correlated. The recurrence period of a 6.2 magnitude earthquake was determined as 63.23 years with the exponential distribution models. Poisson and Gumbel models, on the other hand, indicated, respectively, 102.56 and 101.40 years for the same magnitude. The exponential distribution model resulted in similar values with other models for an earthquake magnitude of ≥ 5.2 as regards the number of annual earthquake recurrence. It was found out that the exponential distribution model produced smaller values than other methods regarding the recurrence periods.
Redox change in sedimentary environments of Triassic bedded cherts, central Japan: possible reflection of sea-level change

Middle Triassic radiolarian bedded cherts in the Mino Belt, central Japan, include a sequence showing an abrupt facies change from the lower to the upper, where grey–black bedded cherts enriched in carbonaceous matter and framboidal pyrite are overlain by brick-red hematitic bedded cherts. Brownish-yellow chert enriched in goethite and purple-red chert occur at the boundary between the grey–black bedded cherts and the brick-red bedded cherts. This facies change is in accordance with stratigraphic variations of geochemical characteristics; the lower section grey–black bedded cherts, compared with the upper section brick-red bedded cherts, are enriched in Ctot and Stot, and are characterized by lower MnO/TiO2, higher FeO/Fe2O3* (total iron as Fe2O3) and more variable Fe2O3*/TiO2 values. Some of the lower section samples, in addition, are characterized by an enrichment in some transition metals (Ni, Cu, and Zn). The covariation of mineralogical and geochemical characteristics indicates that sedimentary environments and diagenetic processes were different between the lower and the upper section bedded cherts. During the deposition of the lower section bedded cherts, the sedimentary environment was anoxic and bacterial sulphate reduction occurred during the early diagenetic stage. In contrast, the upper section bedded cherts were subjected to less reducing diagenetic processes; active sulphate reduction did not occur. The change of sedimentary environment and diagenetic process at the site of deposition is likely to be attributed to the fluctuated concentration of dissolved oxygen in the water mass of a semi-closed marginal ocean basin, which was potentially caused by sea-level change that occurred during Middle Triassic time.
Anomalous Upwelling in Nan Wan: July 2008

Abstract : Tidally induced, sudden temperature drops in Nan Wan, particularly pronounced during the spring tide, often bear ecological consequences. We use an Ocean Nowcast/Forecast System (ONFS) at the US Naval Research Laboratory (NRL) to examine a widely publicized cold-water intrusion event in July 2008, and compare it with what we perceived as a normal intrusion event in June 2007. For a normal cold-water intrusion, cold anomalies eventually propagate away in Forms similar to internal Kelvin waves. For early July of 2008, the NRL ONFS suggested an anomalous, subtidal and essentially eastward current near Nan Wan. The subtidal current, super imposed on the ebb current, blocks the propagation of cold anomalies in the direction of internal Kelvin waves, inducing anomalous and inefficient cold-water dispersal. The NRL ONFS also suggested the anomalous subtidal current as a post-typhoon response to the passage of Typhoon Fengshen.
Benthic Paleoecology in the Givetian: An Example From the Kersadiou Formation (Massif Armoricain, NW France)

Abstract The Kersadiou Formation is well known for its exceptional preservation, diversity, and abundance of mid-Devonian marine fossils. A complete faunal inventory of the Kersadiou Formation over its entire outcrop area is presented here for the first time. Twelve complete sections have been thoroughly sampled from the 28 known outcrops in the Rade de Brest area. The detailed vertical and geographic distribution of 149 identified taxa, coupled with multivariate analyses, allows us to recognize three benthic brachiopod-dominated associations—the Holynetes, Ogorella, and Arcuaminetes associations. These associations reflect a progressive shallowing, which had been previously proposed based on lithological changes from the underlying Quelern Formation to the overlying Tibidy Formation. The corresponding environmental changes are from a protected or restricted marine environment, with a high diversity fauna (Holynetes association), to a shallower, open, higher-energy environment, characterized by a low-diversity assemblage (Arcuaminetes association); the Ogorella association occupies an intermediate position. While the three associations are well developed in the central and eastern parts of the Rade de Brest, only the Arcuaminetes association is well developed in the western outcrop area. This east-west distribution of faunas correlates with the paleoecological gradient evidenced in the studied area.