Investigating Taylor’s frozen turbulence hypothesis in the surface layer at an ideal desert field site using fibre-optic distributed temperature sensing

<p>Taylor’s frozen turbulence hypothesis is the most critical assumption through which time-resolving sensors may be used to derive statistics of the turbulent spatial field. Namely, it relates temporal autocorrelation to spatial correlation via the mean wind speed and is invoked in almost all boundary layer field work. Nevertheless, the conditions and scales over which Taylor’s hypothesis is valid remain poorly understood in the atmospheric boundary layer.</p> <p>As part of the Namib Turbulence Experiment (NamTEX) campaign in March 2020, a pseudo-3D fibre-optic distributed temperature sensing (DTS) array was installed within a 300 x 300 m area in the Namib desert. The array is X-shaped in plan view and contains 16 measurement heights from 0.45 m to 2.85 m. Fibre-optic sensing provides air temperature measurements at unprecedented spatio-temporal density (0.25 m horizontally, 0.17 m vertically, and 1 Hz) and was coupled with a vertical array of traditional sonic anemometer point measurements to investigate the relationship between spatial and temporal temperature fields. The Namib provides an ideal location for fundamental boundary layer research: homogenous flat surfaces, no vegetation, little moisture, strong solar forcing, regular and repeated clear-sky conditions, and a wide range of atmospheric stabilities.</p> <p>Using the NamTEX DTS array we present the first field investigation of Taylor’s hypothesis that considers boundary layer stability and is independent of wind direction. A novel method of 2d horizontal cross-correlation between all possible points of a single height of the DTS is employed to produce spatial ‘maps’ of the turbulent flow, whose velocity, direction, and size may be tracked through time.</p>

An Approach to Natural Gas Valorisation Opportunities Screening Along the Decarbonisation Path

Evolving energy needs and the global energy transition call for proper evaluation of how Natural Gas could support a Decarbonisation path, considering Natural Gas well recognised contribution to GHG emission reduction approaching the ambitious Green World. However, the main question is how gas resources can be properly delivered to satisfy a wide range of markets and usages considering that fundamental driver is the goal of reducing carbon footprint. A methodology was developed, named Gas Master Plan (GMP), which is an integrated study with a novel view, looking to synergic opportunities among energy sources while defining economically sustainable business models and meeting Decarbonisation targets. A Gas Master Plan is a multidisciplinary study assessing the best valorisation routes for Natural Gas resources in a specified country or geographical region. This kind of study analyses gas and energy supply/demand balance, understanding current and future markets and looks for adequate destinations, check existing infrastructures and further possible developments carried by Local Governments or private entities, identify potential gas production for all the involved resources, business modelling, understanding the benefits to the global energy transition targets that such resources could deliver and screening monetization opportunities under a strategic plan view. Thus, a GMP is not just an analysis of upstream volumes to verify whether they match commitments and still fit in their future development plans but it is company-wide joint effort to gather ideas, proposals, topics or issues to be addressed and possible solutions. Broadly speaking resources considered in a typical GMP would be: those under an exploration phase, those just discovered for which a proper development has to be realised, those already in production but for which new market opportunities can be scouted in order to improve their benefit on the energy transition paths while seeking further economic returns. The primary result is to develop a strategy to optimize present production and the development and valorisation of future gas assets, identifying the related GHG profile for each opportunity, supporting the decision-making process on new/future gas initiatives with a coherent plan. The resulting outcomes and conclusions may address specific topics on the short to medium term, like associate to a gas field the proper development project to cover gas and energy commercial demand, or set targets achievable on the medium to long term like supporting a low carbon footprint growth in the energy sector and promoting gas-based industries.

Modeling of Sediment Transport Using Wave Height action in Fialaka Marina

Failaka Island is the second-largest and one of the most important islands of Kuwait from the point of view of tourism located in the north Arabian Gulf. It has a marina constructed in 1979 and managed by the Ministry of Communication (MOC) and a tourism enterprise, and is widely used for its ferry landing facility. The coastal waters around Failaka are turbid and current velocities tend to be as high as ~0.5 m/s during spring tide. The marina basin, with axial plan view dimensions of about 285 m by 260 m experiences shoaling of naturally flocculated fine (cohesive) sediment and coarse sand in the entrance channel and more generally in the southern half of the basin. A particularly noteworthy zone of heavy and visible shoaling is along the inner side of the south breakwater close to the entrance. The marina at Failaka Island is suffering from siltation and sediment deposing issues. This study was carried out numerically to assess the annual sedimentation, sediment direction, and longshore current from locations around the existing marina to help in a suggestion of the solutions to reduce the siltation and sediment deposing based on sediments transport direction on marina entrance. A newly developed numerical solution for annual longshore sediments transport was used to estimate the total sediment transport and its direction. The study shows that the annual sediment transport directions which affect the Fialaka marina entrance are coming from the south to north due to wave action.

Sigmoidal normal faults and evidence for vertical-axis block rotation in an oblique convergent margin: A 3D seismic example from offshore Colombia

Sigmoidal fold and fault geometries are typical kinematic indicators of strike-slip fault zones. We document kilometer-scale, normal faults with sigmoidal plan-view geometries within the dextral pull-apart Bahia Basin, at the rear of the obliquely convergent South Caribbean Deformed Belt, offshore Colombia. Using 3D seismic reflection data calibrated to wells, closely spaced, low-displacement, planar normal faults are mapped within the Miocene strata. A series of seismic horizontal (time) slices and computed seismic attributes are used to interpret the 3D configuration of these faults. The closely spaced faults display an east–west trend with a progressive rotation into a northwest–southeast trend. In map view, the fault traces curve toward their tips, describing a sigmoidal-Z geometry that terminates at discrete northeast–southwest-trending fault zones. The structures observed may correspond to either tension fractures, which form theoretically at 45°, or antithetic shear fractures with normal displacement formed at 50°–70° to the boundaries of a dextral shear zone. These scenarios lead to a clockwise block rotation of between 20° and 40° within the shear zone. This study shows the first example of vertical-axis block rotations observed offshore in the western end of the South Caribbean margin and is an important example of the use of 3D seismic data to identify rotations where paleomagnetic studies are not available.

Plan-view TEM observation of a single-domain κ-Ga2O3 thin film grown on ε-GaFeO3 substrate using GaCl3 precursor by mist chemical vapor deposition

We demonstrated the growth of a single-domain κ-Ga2O3 thin film on ε-GaFeO3 by using an organic-free compound as a precursor for mist chemical vapor deposition. X-ray diffraction analysis revealed that an 87-nm-thick κ-Ga2O3 thin film was grown almost coherently with slight lattice relaxation. The surface morphology of the κ-Ga2O3 thin film exhibited a step-terrace structure without island growth. Furthermore, plan-view TEM observations revealed that the κ-Ga2O3 thin film grown on ε-GaFeO3 had a single domain, whereas the previously reported κ-Ga2O3 thin film grown on AlN template had a domain structure.

Coarse-grained meandering distributive fluvial system of the basal Cedar Mountain Formation, U.S.A.

ABSTRACT The analysis of downstream changes in ancient fluvial systems can better inform depositional models for foreland-basin systems. Herein we analyze the basal deposits of the Early Cretaceous Cedar Mountain Formation of Utah to better understand the variety of fluvial deposits present and to develop a depositional model for the Sevier foreland basin. We also evaluate the long-held interpretation of a braided origin for these deposits and document numerous examples of point-bar deposition in highly sinuous meandering rivers by analysis of large (20 to 60 km2) plan-view exposures. These plan-view exposures allow comparisons between planform and cross-sectional geometries. The study utilizes outcrop data, virtual outcrop models, and satellite imagery to develop a facies model and analyze the architecture of channel bodies in the Buckhorn Conglomerate and Poison Strip Sandstone of the Cedar Mountain Formation. We document downstream (west to east) decreases in lateral channel migration, sinuosity, channel amalgamation, grain size, and percent of fluvial channel facies (conglomerate and sandstone). Fluvial channel deposits occur arranged into larger stratal bodies: multistory–multilateral channel bodies that are dominantly composed of clast-supported conglomerate in the west to a mix of multistory, multilateral, and isolated channel bodies composed of matrix-supported conglomerate in the east. The median width of highly sinuous point bars is similar across the field area (344 m to 477 m), but the inclusion of narrower (median = 174 m), low-sinuosity bar elements in the east indicates an overall reduction in lateral channel migration and sinuosity downstream. Net-to-gross values range from 100% in much of the western outcrops to as low as 38% in the east. Paleocurrent analysis reveals a transverse (west to east) paleoflow for the study interval that merges with axial (south–north) paleoflow near the Utah–Colorado state line. We estimate 104 m3/s-scale discharge and 106 kilometer-scale drainage area for axial rivers based on paleohydraulic analysis which represents a significant part of the Early Cretaceous continental-scale drainage. The observed downstream trends in lateral channel migration, sinuosity, channel amalgamation, grain size, and net-to-gross for the basal Cedar Mountain Formation are consistent with expected trends for sinuous single-thread distributive fluvial systems and are similar to observed trends in the Jurassic Morrison Formation. Medial (Buckhorn Conglomerate) to distal (Poison Strip Sandstone) zones are preserved and span the forebulge to backbulge depozones of a foreland-basin system. Postulated deposits of the proximal distributive fluvial system have been removed during erosion of the foredeep depozone. The easternmost Poison Strip Sandstone and coeval Burro Canyon Formation represent deposits of an axial system at which western-sourced distributive fluvial systems end. Distributive fluvial systems dominate modern foreland basins, and this study suggests that they may constitute a significant proportion of ancient successions.

Accurate Sub-micron Device Delayering of Plan View TEM Specimens By Ar Ion Milling

With the introduction of new materials, new device structures, and shrinking device dimensions, failure mechanisms evolve, which can make identifying defects challenging. Therefore, an accurate and controllable delayering process to target defects is desirable. We present a workflow comprised of bulk device delayering by broad Ar ion beam milling, plan view specimen preparation by focused ion beam tool, followed by site-specific delayering by concentrated Ar ion beam milling. The result is an accurately delayered device, without sample preparation-induced artifacts, that is suitable for uncovering defects during physical failure analysis.

Automated Cell Layer Counting and Marking at Target Layer of 3D NAND TEM Samples by Focused Ion Beam

The plan-view TEM analysis has been used for 3D NAND flash memory to analyze metrology and chemical of channel holes. Focused Ion Beam (FIB) is one of the most powerful techniques for precise location sampling in nanometer-scale for Transmission Electron Microscope (TEM) sample preparation. As semiconductor technology improves continuously, 3D NAND is requiring higher stacks to increasing the capacity of storage. In general, an operator counts the cell layer manually to reach the desire layer on TEM sample before thinning. It is not easy way to make TEM samples at the exact desired layer. To make it easier, automatic cell layer counting workflow is introduced in this paper. This progress is carried out until the desired target cell is reached. Furthermore, marking is performed on the target cell layer. This automation recipe is able to offer simple process to count the desired cell layer without manual action and make TEM sample preparation easily.

Materials from Dwelling 2 on Suchu Island, the Lower Amur (1977 Season, Excavation III)

This article presents the fi nal results of excavations at one of the largest Neolithic sites in northeastern Asia— a settlement on Suchu Island on the Amur. Most of the rich collection (3967 spec.), owned by IAET SB RAS (stone tools, ceramics, ornaments, and artistic and ritual artifacts), has not been described before. This publication focuses on the analysis of artifacts from dwelling 2 (excavation III, 1977). We describe the construction of this semi-underground dwelling, circular in plan view. The typological analysis of the lithics indicates a complex economy. Many of them (arrowheads, projectile points, inserts, knives, plummets) relate to hunting and fi shing, and to processing carcasses (end-scrapers, scrapers, burins, combination tools), others are chopping tools. The distinctive feature of the lithics is that some are bifacial. The analysis of the ceramics suggests that they belong to the Late Neolithic Voznesenovskoye culture. The use of binocular microscopy allowed us to assess the technological and constructive properties of the ceramics, as well as their morphological, decorative, and functional features. Non-ut ilitarian artifacts shed light on the worldview of the Suchu people. The collection dates to the mid-second millennium BC.

Traces of the Dahaean and Sarmatian Cultural Legacy in Ancient Turan and Old Rus

This study examines the migrations of the Dahae and Sarmatians—the two related early nomadic peoples of Middle Asia and Eastern Europe—directed to the south and west of their homeland. Archaeological, written, and folkloric sources make it possible to trace the migrations of the Dahae and Sarmatians over several centuries preceding the spread of Islam in Central Asia and of Christianity in Old Rus. The study focuses on mortuary monuments, temples, and sanctuaries, cross-shaped in plan view, of migrants and their descendants. A detailed analysis of the major southward migration of Dahae from the Lower Syr-Darya in the late 3rd to early 2nd BC is presented. This migration had a considerable effect on ethnic and cultural processes in Middle Asia. The migration aimed at conquering the lands of Alexander the Great’s descendants, who were rapidly losing control over them. Features of Dahaean culture are noticed in town planning, architecture, mortuary rites, armor, etc. over the entire territory they had captured. Southward migration of the descendants of the Dahae—people of the Kaunchi and Otrar cultures—from the Syr-Darya, led by the Huns, was part of the Great Migration. The Kaunchi people headed toward the oases of Samarkand and Kesh, the Otrar people toward the oasis of Bukhara, and those associated with the Dzhetyasar culture toward the Qarshi oasis. It is demonstrated that while the cross-shaped plan view of religious structures turned into the eight-petaled rosette, the fu neral rite did not change, remains of burials and charcoal are observed everywhere. Relics of the ScythoSarmatian legacy are seen in the culture of Old Rus. For instance, remains of the sanctuaries of Perun are walls and ditches arranged in a cruciform or eight-petaled fashion, fi lled with charcoal and bones of sacrifi ced animals, with a statue of the supreme Slavic deity, in the center. Early sanctuaries of Perun in Kiev and Khodosovichi were cruciate in plan view, while later ones on the banks of the Zbruch and the Volkhov rivers had octopetalous plans. Apparently they were infl uenced by the architectural traditions of Dahae and Sarmatians, who took part in the ethnogenetic processes in both Old Rus and Turan.