Meters In Length Research Articles

Homogeneity of Needleless Electrospun Nanofiber Mats.

Nanofiber mats can be electrospun by different techniques, usually subdivided into needle-based and needleless. The latter allow for producing large-area nanofiber mats, e.g., with a width of 50 cm and lengths of several meters, if electrospinning proceeds for several hours, depending on the required thickness. Even spinning smaller samples, however, raises the question of homogeneity, especially if defined mechanical properties or a defined thickness is required, e.g., for filtration purposes. Very often, only the inner parts of such electrospun nanofiber mats are used to avoid too high variation of the nanofiber mat thickness. For this study, we used wire-based electrospinning to prepare nanofiber mats with slightly varying spinning parameters. We report investigations of the thickness and mass per unit area, measured on different positions of needleless electrospun nanofiber mats. Martindale abrasion tests on different positions are added as a measure of the mechanical properties. All nanofiber mats show unexpectedly strong variations of thickness, mass per unit area, and porosity, as calculated from the apparent density of the membranes. The thickness especially varied by nearly one order of magnitude within one sample, while the apparent density, as the most uniform parameter, still showed variations by more than a factor of two within one sample. This shows that even for apparently highly homogeneous areas of such nanofiber mats, variations cannot be neglected for all potential applications.

Assessment of long tubing in measuring atmospheric trace gases: applications on tall towers

Negligible losses were observed for many atmospheric trace species after traversing the PFA Teflon tubing that was hundreds of meters in length.

Evolution of Tiling-like Crack Patterns in Maturing Columnar Joints.

Fracture or cracking essentially involves the formation of new interfaces. These patterns are usually studied as two-dimensional mosaics. The new surface that opens up is in the third dimension, along the thickness of the sample. The thickness is usually very small compared to the lateral dimensions of the pattern. A spectacular and distinctive departure from these everyday examples of cracks are columnar joints. Here, molten volcanic lava, by the sea, cools and cracks under appropriate thermal and elastic conditions, causing the crack system to grow downward, creating long, vertical columns with polygonal cross-section. The focus of this paper is the study of the elongated interfaces of these columns: how the cross-section of their outlines gradually undergoes a metamorphosis from a disordered-looking Gilbert tessellation to a well-ordered hexagonal Voronoi pattern. As the columns grow downward to lengths of several meters (in natural systems), their outline continuously changes, the center may shift, causing the column to twist. For the first time, the evolution of these crack mosaics has been simulated and mapped as a trajectory of a 4-vector tuple in a geometry-topology domain. The trajectory of the columnar joint systems is found to depend on the crack seed distribution and crack orientation. An empirical relationship between the system energy and the crack mosaic shape parameter λ has been proposed on the basis of principles of fracture mechanics. The total system energy shows a power-law dependence on λ with the exponent β ∼ 0.3 and λ ≈ 0.75 at crack maturation. The parameter values are validated by matching the proposed relation with energy estimates existing in the literature. The relation not only matches the visible changes in geometry but also provides a feasible measure of the energy of the system. The geometric energy for the polygonal mosaics in the transverse section has also been estimated as a function of time. The geometric energy moves toward a minimum as the mosaic becomes more Voronoi-like at maturation.

GeoCLR: Georeference Contrastive Learning for Efficient Seafloor Image Interpretation

This paper describes georeference contrastive learning of visual representation (GeoCLR) for efficient training of deep-learning convolutional neural networks (CNNs). The method leverages georeference information by generating a similar image pair using images taken of nearby locations, and contrasting these with an image pair that is far apart. The underlying assumption is that images gathered within a close distance are more likely to have similar visual appearance, where this can be reasonably satisfied in seafloor robotic imaging applications where image footprints are limited to edge lengths of a few meters and are taken so that they overlap along a vehicle’s trajectory, whereas seafloor substrates and habitats have patch sizes that are far larger. A key advantage of this method is that it is self-supervised and does not require any human input for CNN training. The method is computationally efficient, where results can be generated between dives during multi-day autonomous underwater vehicle (AUV) missions using computational resources that would be accessible during most oceanic field trials. We apply GeoCLR to habitat classification on a dataset that consists of ~86,000 images gathered using an AUV. We demonstrate how the latent representations generated by GeoCLR can be used to efficiently guide human annotation efforts, where the semi-supervised framework improves classification accuracy by an average of 10.2% compared to the state-of-the-art SimCLR using the same CNN and equivalent number of human annotations for training.

Investigation of Sensor-Based sorting and selective comminution for pre-concentration of an unusual parisite-rich REE ore, South Namxe, Vietnam

The South Namxe deposit in Vietnam contains unusually high quantities of parisite, in addition to minor quantities of other fluorocarbonates, such as synchysite and bastnaesite. Together these minerals constitute the main REE-bearing minerals. This carbonatite-related deposit presents tabular (dykes) or lens-form ore bodies, up to several tens of meters wide and tens to hundreds of meters in length, that are hosted in Permian limestone and Triassic basalts. The main gangue minerals in the ore bodies are from the barite-celestine solid solution series, ankerite and calcite. It was considered necessary to assess the different grain characteristics presented by the presence of parisite intergrowths and its association with minerals of the barite-celestine solid solution series to structure a probable initial beneficiation strategy. Mineral liberation analysis revealed that an optimal liberation particle size between 45 µm and 90 µm could be achieved without overgrinding the material. Additionally, it showed a strong mineral association between fluorocarbonates, baryto-celestine, and calcite. Grinding below 100 µm is necessary. One substantial energy saving potential is removing the host rock prior to grinding. The potential for pre-concentration with sensor-based sorting and selective comminution is investigated in a pre-study. Sensor-based sorting using X-ray transmission resulted in an enrichment of REE by a factor of 4, a reduction of the mass stream down to approximately 30%, and a loss of rare earths below 2%. Selective comminution using a pin mill, at a circumferential speed of 20 m/s, yielded a recovery of 96.5% of REE minerals and allowed rejection of 27% of barren material. This shows that both selective comminution and sensor-based sorting can be considered as complementary beneficiation steps when processing these REE ores.

Design and development of an automatic kilcha (skeining) machine

Denier test for raw silk testing requires skeins of 450 metres length in slightly twisted form (Kilcha), and the existing processis done manually with skein winder, that has few drawbacks, which are low production, quality and higher time and labour.Hence, the present study proposed to design and develop a machine to rectify the above drawbacks for faster production withgood-quality silk skeins, and to reduce testing time and labours involved in work. The innovated machine is designed anddeveloped as automatic skeining (Kilcha) machine and the result showed improvement in production, and quality with reductionin time and labour compared to the manual winder.

Accuracy and spread of nest search behaviour in the Saharan silver ant, Cataglyphis bombycina, and in the salt pan species, Cataglyphis fortis

Desert ants of the genus Cataglyphis are renowned for their navigation abilities, especially for their beeline homing after meandering foraging excursions reaching several hundreds of meters in length. A spiralling nest search is performed when an ant misses the nest entrance upon completing its homebound travel. We examined the nest search behaviours of two desert ant species dwelling in different habitats—Cataglyphis bombycina living in the dunes of the Sahara and Cataglyphis fortis found in the salt pans of North Africa. The two species show distinct differences in walking behaviour. C. bombycina performs a strict tripod gait with pronounced aerial phases, high stride frequencies, and extremely brief ground contact times. In view of these peculiarities and the yielding sand dune substrate, we hypothesised that homing accuracy, and namely distance measurement by stride integration, should be lower in C. bombycina, compared to the well-studied C. fortis with less specialised walking behaviour. We tested this hypothesis in ants’ homebound runs from a feeding site in a linear channel setup. Surprisingly, the accuracies of nest searches were similar in the two ant species, and search accuracy was also independent of the walking substrate, soft dune sand or a hard floor. The spread of the nest search, by contrast, differed significantly between the two species, C. bombycina exhibiting a larger search spread. This may be interpreted as an increased path integration uncertainty due to the above locomotor specialisations, or as a compensation strategy accounting for the silver ants’ particular environmental and behavioural situation.

The Forms of Linear Structure of Overland Flow in Medium-Height Mountain Regions: Case Study of the Sikhote Alin

Large subsurface streams on steep slopes have stable positions with distinct catchment areas (drainage basins), linear shapes, and lengths of tens and hundreds meters. They form a closed drainage network with a role and scale similar to the primary hydrographic network and serve as specific hydrological objects—drains. Drains are widespread in the medium-height humid mountain zone, where they account for the formation of a considerable portion of slope runoff. The hydrographic and hydrological characteristics of drains have been examined in small river basins of the Sikhote Alin with the use of field studies, hydrometric measurements, and large-scale topographic surveys.

Stratigraphic correlation and splice generation for sediments recovered from a large-lake drilling project: an example from Lake Junín, Peru

Sediment records from deep-drilling projects such as those carried out by the International Continental Scientific Drilling Program are often tens to hundreds of meters in length. To ensure the complete recovery of a stratigraphic section, a basin is usually cored multiple times in adjacent holes so that gaps between sequential cores, poorly recovered sections, or intervals affected by disturbance can be bridged or replaced with sediments from another hole. Stratigraphic correlation, the alignment of stratigraphically-equivalent horizons in cores from different holes in a common-depth scale, and splice generation, the integration of the most-representative core sections into a composite-stratigraphic section, are essential steps in this process to both evaluate and synthesize the recovered-sediment record and focus the scientific analyses. However, these undertakings can be complex and are inherently subjective, making the need for the development of a single robust stratigraphic section early in the project critical to its success. Despite this, the steps between core recovery and on-splice data generation are rarely published in sufficient detail to allow reconstruction, or refinement, of the composited record at a later date. To increase the transparency of how the composite record is created, and to provide a template for future projects, we detail the step-by-step approaches and decisions involved in generating the composite-depth scale and complete-stratigraphic splice following recovery of sediments from Lake Junin, Peru. We first explain the details and nuances of different drilling-depth scales before describing how we integrated different physical property records to generate the composite-depth scale and complete-stratigraphic splice. Here, we show that due to the complex stratigraphy in the Lake Junin sediments, high-resolution line-scan images of the cores offer millimeter-scale precision for construction of the primary-stratigraphic splice at a resolution not afforded by other physical property data. Finally, through comparison of the spliced record to physical-property records acquired in situ on the borehole, we demonstrate that the stratigraphic splice is an accurate representation of the sediment accumulated in the Lake Junin basin.

Love and Dishonour in Elizabethan England: Two Families and a Failed Marriage, by Ralph Houlbrooke

One beautiful autumn afternoon in 1979, Professor Ralph Houlbrooke discovered a tightly rolled vellum strip of over five metres length in the old Public Record Office, Chancery Lane. It described in poignant detail the clandestine marriage and marital breakdown of a late-sixteenth-century couple from East Anglia, Charles and Elizabeth Forth (née Jerningham). Captivated immediately, Houlbrooke resolved to revisit the case in his retirement. Thirty-nine years later, the resulting monograph has been published. Meticulously researched, this magnificent microhistory unravels the twists and turns in the (mis)fortunes of two families, culminating in a fateful marriage. Chapters One and Two introduce the Jerninghams, a long-established Catholic family from Suffolk, and describe their rise and ruin between the 1300s and 1500s, with a particular focus on the escapades of John Jerningham, the father of the book’s protagonist, Elizabeth Forth. In Chapter Three, we meet the contrasting Forth family, descendants of wealthy Hadleigh clothiers, who acquired substantial landholdings in the early 1500s, and became highly respected members of the Protestant elite.

Nanoscale Molecular Fractionation of Organic Matter within Unconventional Petroleum Source Beds

Fractionation of petroleum during migration through sedimentary rock matrices has been observed across lengths of meters to kilometers. Selective adsorption of specific chemical moieties at mineral...

Precision loss measurements in short lengths of optical fibre by reflectometry without using Rayleigh scattering

To improve accuracy of light attenuation measurements in optical fibres, especially in short ones, tens and hundreds of metres in length, we propose rejecting a conventional reflectometric approach based on Rayleigh scattering intensity measurements. To this end, we propose for the first time the use of boson peaks in Raman scattering, which, on the one hand, produce no interference effects and no related noise in reflectograms, and, on the other, lie within the C-band. Even at a fibre length as short as 50 m, the attenuation measurement error does not exceed 0.002 dB km−1. We demonstrate the possibility of compensating for the temperature variation of boson peak intensity by concurrently obtaining a reflectogram for the anti-Stokes line of the fundamental Raman band.

Search for heavy charged long-lived particles in the ATLAS detector in 36.1 fb−1 of proton-proton collision data at s=13 TeV

A search for heavy charged long-lived particles is performed using a data sample of 36.1 fb$^{-1}$ of proton-proton collisions at $\sqrt{s} = 13$ TeV collected by the ATLAS experiment at the Large Hadron Collider. The search is based on observables related to ionization energy loss and time of flight, which are sensitive to the velocity of heavy charged particles traveling significantly slower than the speed of light. Multiple search strategies for a wide range of lifetimes, corresponding to path lengths of a few meters, are defined as model-independently as possible, by referencing several representative physics cases that yield long-lived particles within supersymmetric models, such as gluinos/squarks ($R$-hadrons), charginos and staus. No significant deviations from the expected Standard Model background are observed. Upper limits at 95% confidence level are provided on the production cross sections of long-lived $R$-hadrons as well as directly pair-produced staus and charginos. These results translate into lower limits on the masses of long-lived gluino, sbottom and stop $R$-hadrons, as well as staus and charginos of 2000 GeV, 1250 GeV, 1340 GeV, 430 GeV and 1090 GeV, respectively.

Electron Beam Welding of Large Components for The Nuclear Industry

The nuclear industry requires rapid and high quality joining of large scale components. Electron beam welding (EBW) has the potential to respond to these requirements. The aim of Nuclear Advanced Manufacturing Research Centre (Nuclear AMRC) is to develop solutions for the future application of this technology. One example is the research on deep penetration EBW for joining large scale pressure vessels for small modular nuclear reactors. This will require several circumferential welds of ~ 6 metres length each. In addition joining of sections of the upper and lower vessel heads and of HIP sections with varying wall thickness must be developed. In collaboration with the US Electric Power Research Institute (EPRI) the Nuclear AMRC is working to produce two-thirds scaled demonstrators of the lower and the upper pressure vessel assembly (based on a generic NuScale model). 100 mm deep single track, full penetration welds of pressure vessel steel have been demonstrated. In addition, within 26 minutes joining of shells was achieved with 6 metres long circumferential welds (78 mm full penetration). In future the joining of complex sections and sections with variable thickness will be investigate.

Sewability interdependence on rigid structures

Sewability is the ability of the fabric to be sewn without faults and represents the ease of fabric processing at a satisfactory level. It can be used to predict problems which may occur in the garment sewing stage and it can be accurately measured using the L&M sewability tester as a function of that needle penetration force though the fabric. Sewability is attributed to fabric properties, pretreatment, finishing, sewing conditions and mishandling. Fabric softeners affect the ease of sewing processing of garments, which is mostly reflected by the needle penetration force. The current work was driven by previous study focused on the analysis of factors affecting the sewability of cellulosic woven fabrics of a wide range of designs and constructions, where the influence of several fabric properties on the needle penetration force had been investigated, revealing the existence of a relationship between the inherent properties of mass per square metre, breaking strength and bending length. However, the in-depth statistical analysis had shown that rigid structures follow a different trend in comparison to the light ones. In the current work, thin and light structured fabrics were excluded from the investigation and focus was given exclusively to the rigid structures of higher mass per square metre fabrics which are known to be problematic in sewing stage. Although the investigation was confined to the main three inherent properties which had proven to influence needle penetration, it included fabric treatments of washing and softening on the samples. Results show an increase in the interdependency of the studied properties while treatments show a minimal effect probably to low level of application.

Prediction of Ground Behaviour for Rock Tunnelling

Studies have shown that the ground behaviour for rock tunnelling depends on the rock mass strength and the in situ stresses. The rock mass strength, to a considerable extent, is governed by the presence of joints/discontinuities and their properties. Three aspects concerning the joints are primarily responsible for the reduction in the strength and are measurable in the field: (i) Joint frequency or number of joints per metre length in the direction of loading (Jn), (ii) orientation of critical joint set with respect to loading direction (β), and (iii) shear strength along the critical joint set (r). These three factors have been combined into another rock mass parameter, namely, the joint factor (Jf). Thus, joint factor has been selected as one of the parameters for developing the empirical correlation for predicting the ground behaviour. In addition to joint factor, the tunnel size and the tunnel depth are the other two involved parameters. Details of data and the process of developing the empirical correlations are discussed in the paper. The proposed empirical correlations for non-squeezing and squeezing ground behaviours have been validated by comparing the results with the observed data obtained from various sections of one Himalayan tunnel recently excavated in the state of Jammu and Kashmir in India.

Divertor leg filaments in NSTX-U

This paper presents the first observation of divertor localized turbulence in the NSTX-Upgrade spherical tokamak. Previous work in NSTX discharges (Maqueda et al 2010 Nucl. Fusion 50 075002) described fluctuations on the divertor target due to blobs generated on the low field side midplane. In the region that shows disconnection from upstream turbulence (private flux region and proximity of the strike point), divertor-localized fluctuations are observed via imaging of C III and D-α emission in diverted L-mode discharges and are characterized in this paper. Field-aligned filaments connected to the divertor target plate are radially localized at the separatrix on the outer divertor leg and in the private flux region on the inner divertor leg. These are limited to the region below the X-point with fluctuation levels up to 10%–20%. The filaments have comparable poloidal and radial correlation lengths (10–100 ion gyroradii ) and parallel correlation lengths of several meters. Toroidal mode numbers are in the range of 10–30 and 2–10 for outer and inner leg filaments. The poloidal motion of outer leg filaments has the same direction and comparable magnitude to advection due to drift calculated by the multi-fluid edge transport code UEDGE with inclusion of cross field drifts. Disconnection between inner and outer leg filaments as well as the absence of correlation with upstream turbulence support the hypothesis of X-point disconnection for divertor leg filaments. Simulations with the ArbiTER linear eigenvalue solver and a resistive-balooning model were performed with a simulation grid limited to the divertor legs. Instabilities localized to the bad curvature side of the divertor legs were observed, in qualitative agreement with the experiment.

The loss of large wood affects rocky mountain trout populations

AbstractWestern U.S. rivers are currently influenced by legacy effects of reduced large wood (LW) loading and retention that has substantially reduced in‐stream habitat complexity. Large wood is typically associated with streams in undisturbed old‐growth forest and in the correct geomorphic context can drastically alter stream and valley habitat complexity. Streams withLWare typically multichannel and depositional, while streams lackingLW, due to relatively recent wildfire or logging (<200 years ago), are usually single channelled and erosional. We compared population biomass and individual growth rates of Brook TroutSalvelinus fontinalisin streams across a gradient of wood volumes. At both the square metre and valley length scales, standing stock biomass of aquatic invertebrates was the best predictor of trout biomass. However, at the valley scale, the number of pools was important in predicting trout biomass in combination with standing stock biomass of aquatic invertebrates. Individual growth rates of age‐1 Brook Trout were negatively affected by increasing density; however, growth rates for the largest and smallest individuals at each site were unaffected by density. Our results suggest the pool habitat created byLWacts synergistically with prey availability to dramatically increase trout populations. However, in streams lacking LW, negative effects of detrimental land use practices have persisted >100 years, suggesting that recovering lost animal production in mountain stream networks will only occur at decadal to century time scales.

Liquid-Crystal Active Tamm-Plasmon Devices

For the surface electronic states of a metal, the Tamm plasmonic (TP) mode can be excited without an additional phase-matching component, but in a typical device the TP resonance wavelength is fixed, which is quite limiting. This work develops an approach to tuning TP resonance by incorporating a thin layer of liquid crystal (LC) into the design. Here phase retardation by the LC layer is an ensemble effect, due to the entire layer, not just the molecules at the metal's surface, as in devices based on surface-plasmon polaritons (SPPs). Also unlike SPP systems, the proposed structure is highly amenable to mature thin-film processing, for scalability to lengths of several meters.

Between a ripple and a dune

Bedforms in deserts include both small ripples and sand dunes that can reach tens to hundreds of metres in length — with seemingly little in between. It now looks as though intermediate-sized megaripples do appear if the conditions are just right.