Narrow Surfaces Research Articles

Tracing Dissolved Lead Sources in the Canadian Arctic: Insights from the Canadian GEOTRACES Program

This study addresses an important knowledge gap in the distribution of lead (Pb) in the Arctic Ocean, by presenting dissolved Pb concentrations from samples collected during the GEOTRACES Canadian cruise in 2015. Dissolved Pb showed an increase in concentration from the Canada Basin toward Baffin Bay and the Labrador Sea. Canada Basin was the most isolated region from anthropogenic Pb inputs with low background concentrations (1.4–6.2 pmol kg–1) across most of the basin, although higher Pb features from the advection of Pacific-derived waters and sea ice meltwater were present. Likewise, high-Pb peaks (13.5–26.6 pmol kg–1) along narrow isopycnal surfaces (σθ, 27.4–27.6) in Baffin Bay were attributed to the advection of North Atlantic waters spreading a high-Pb signature into the bay, contrasting with the low values (2.5–7.4 pmol kg–1) present in the mixed layer, Arctic and Baffin Bay deep waters. The Labrador Sea, largely influenced by the recirculation of North Atlantic waters, had the highest Pb concent...

Moving in complex environments: a biomechanical analysis of locomotion on inclined and narrow substrates.

Characterisation of an organism's performance in different habitats provides insight into the conditions that allow it to survive and reproduce. In recent years, the northern quoll (Dasyurus hallucatus) - a medium-sized semi-arboreal marsupial native to northern Australia - has undergone significant population declines within open forest, woodland and riparian habitats, but less so in rocky areas. To help understand this decline, we quantified the biomechanical performance of wild northern quolls as they ran up inclined narrow (13 mm pole) and inclined wide (90 mm platform) substrates. We predicted that quolls may possess biomechanical adaptations to increase stability on narrow surfaces, which are more common in rocky habitats. Our results showed that quolls have some biomechanical characteristics consistent with a stability advantage on narrow surfaces. This includes the coupled use of limb pairs, as indicated via a decrease in footfall time, and an ability to produce corrective torques to counteract the toppling moments commonly encountered during gait on narrow surfaces. However, speed was constrained on narrow surfaces, and quolls did not adopt diagonal sequence gaits, unlike true arboreal specialists such as primates. In comparison with key predators, such as cats and dogs, northern quolls appear inferior in terrestrial environments but have a stability advantage at higher speeds on narrow supports. This may partially explain the heterogeneous declines in northern quoll populations among various habitats on mainland Australia.

Solid-shelled microspheres loaded with solvent as diluents for extracting blockages by heavy-oil and asphaltene precipitates

A novel type of solid-shelled microspheres was prepared by emulsion templating technique through layer-by-layer self assembly. The regulation controlled by different payloads, surfactants, 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS) ratio produced three solid-shelled microspheres with various morphology, sizes, shell thicknesses and brittleness. Such microspheres can be considered as diluent-loaded eggs that can be cracked when forced between narrow rock surfaces or against blocking fluid flow particles. The structural characteristics, size distribution, stability, breakable and release behavior of three payload-in-silica microspheres were investigated by optical microscopy techniques and scanning electron microscopy (SEM) technique, dynamic light scattering (DLS), zeta potential, and ultraviolet-visible (UV–vis) spectroscopy. The results indicated that these three microspheres were relatively uniform in size (1–5 μm) and had a smooth surface with shell thicknesses of 40–120 nm, which also possessed excellent stability. Yet the brittleness of silica shell was obviously different for three solid-shelled microspheres, in detail, the silica shell of toluene microspheres was more brittle and easier to be ruptured than hexane microspheres under external hydrodynamics forces. Sand column tests revealed that the easy-broken toluene-in-silica microspheres prepared from tween-80 template matched the pore throat of reservoir better and achieved higher heavy oil recovery efficiency (94.60%). Such breakable microspheres can provide a selective and targeted diluting approach to extract blockages by heavy-oil and asphaltene precipitates.

Mechanical and Hygroscopic Properties of Longitudinally-Laminated Timber (LLT) Panels for the Furniture Industry

One likely reason why cross-laminated timber (CLT) panels are not applied in furniture designing is their unaesthetic appearance, with a crosswise arrangement of layers visible on narrow surfaces of furniture panels. The objective of this investigation was to manufacture and determine physic-mechanical properties of solid and cell Longitudinally-Laminated Timber (LLT) panels. The cognitive goal of the performed experiments was to determine orthotropy, linear elasticity moduli, and bending strength of LLTs. It was also decided to ascertain swelling coefficients of composites caused by changes in air humidity. Advantageous MOE and MOR values of LLTs were determined in relation to similar solid panels. In addition, it was demonstrated that, for furniture panel designing, it was rational to employ facings from beech wood as well as cores from beech wood free from anatomical defects.

Effective elastic properties and initial yield surfaces of two 3D lattice structures

The effective elastic properties of two bending-dominated lattice structures subjected to uniaxial loading are investigated with using the classical beam theory. In particular, considering the coupling effect of axial force and bending moment, a theoretical approach for predicting the yield surface of lattice structures under complex stress state is proposed. The analytical solutions are verified by comparing the predictions with finite element method (FEM) simulations. It is shown that the deformation mode of the struts is strongly dependent on the loading directions, and the lattice can be either bending-dominated or stretching-dominated in different stress states, resulting in narrow yield surfaces. The comparisons reveal that both the theoretical analysis and numerical simulations present a considerably good description of the initial yield surfaces, which provides new insight into understanding the mechanical behaviors of the lattice structures and applications in lightweight structures.

Analysis of glenoid inter-anchor distance with an all-suture anchor system

BackgroundAll-suture anchors used in arthroscopic shoulder stabilization employ small diameter anchors, which allow greater placement density on narrow surfaces such as the glenoid. There is no consensus in the literature about how close to one another two anchors may be implanted. PurposeThe purpose of the present study is to compare the strength characteristics of two all-suture anchors placed in cadaveric human glenoid at variable distances to one another, in order to determine the minimum distance required for optimal strength. MethodsTwelve fresh-frozen human cadaveric glenoids were implanted with 1.4 mm all-suture anchors at varying inter-anchor distances. Each glenoid was used for four tests, for a total of 48 tests. Anchors were implanted adjacent to one another or with 2, 3, or 5 mm bone bridges between pilot holes. The glenoids then underwent pullout testing using a test frame with a 5N preload followed by displacement of 12.5 mm/s. The primary outcomes were stiffness, failure strength, and ultimate strength. ResultsStiffness was 13.52 ± 3.8, 17.97 ± 5.02, 17.59 ± 4.65 and 18.95 ± 4.67 N/mm for the adjacent, 2, 3, and 5 mm treatment groups, respectively. The adjacent group had a significantly lower stiffness compared to the other treatment groups. Failure strength was 48.68 ± 20.64, 76.16 ± 23.78, 73.19 ± 35.83 and 87.04 ± 34.67 N for the adjacent, 2, 3, and 5 mm treatment groups, respectively. The adjacent group had a significantly lower failure strength compared to the other treatment groups. Ultimate strength was also measured to be 190.59 ± 140.93, 268.7 ± 115.1, 283.23 ± 118.43, and 291.28 ± 118.24 for the adjacent, 2, 3, and 5 mm treatment groups, respectively. ConclusionsThis biomechanical study provides evidence that 1.4 mm all-suture anchors demonstrate similar strength characteristics when placed at least 2 mm or greater from one another. When 1.4 mm all-suture anchors were placed adjacent to one another, there was an observed decrease in failure strength and stiffness. Clinical relevanceThis study suggests that 1.4 mm all-suture anchors may be placed as close as 2 mm to one another while preserving strength characteristics.

Aux prémices du Gravettien dans le Nord-Ouest européen : étude de la production des pointes lithiques à Maisières-Canal (province de Hainaut, Belgique)

Aux prémices du Gravettien dans le Nord-Ouest européen : étude de la production des pointes lithiques à Maisières-Canal (province de Hainaut, Belgique)

Development of In-pipe Inspection Robot

In recent years, robotics has become an important domain in the field of engineering. It plays a crucial role in various fields, one of them being inspection purpose. In-pipe inspection robots are necessary for the safe and smooth running of industries. Problems arising in the piping network may lead to loss of the transported medium and leakage of which often affect the environment. Hence, it must be continuously inspected which involves large amount of labour. Also, the working environment usually involves possible exposure to hazardous chemicals or gases, humid and low oxygen content air, zones inaccessible to human hands, etc. Robots can act in an inaccessible environment and also reduce human effort. Therefore, inspection robots are strongly demanded. The main objective of the present work is to design a miniature robot which can adapt to narrow surfaces. In-pipe inspection robot using DC Motor (conventional actuators) is developed for this purpose. Modelling of the robot is done in SolidWorks. Simulations were performed for horizontal and vertical configuration of pipe and results were plotted. A prototype is developed and experiments were carried out in horizontal pipe. A comparison of results for different parameters obtained from simulation study and experimental work was done.

Influence of the Palaeo-Landslides on the Project of Rehabilitation of a National Road in the Southern Carpathian Area

The mountain Paduchiosu is a part of the Southern Carpathians, in the South-Eastern Bucegi National Park. Significant palaeo-landslides occur on the Eastern slope of the mountain Paduchiosu, affecting the DN 71 alignment, between Valea Dorului and Valea Carpinis, on a length of approx. 10 km [1]. The palaeo-landslides occur along the tectonic contacts of various cretaceous formations. The landslides occur both at the level of Quaternary deposits, forming the alteration layer of the old geological formations (alluvial, deluvial and colluvial soil deposits), and at the level of Pre-Quaternary geological formations, whose structure is clayey-marl, or within the harder rocky formations, with seams of clayey – marl nature also. Two large palaeo-landslides can be distinguished: landslide I, affecting the national road alignment between pk 96 and 101+500, with sliding orientation towards South and South-West and landslide II, affecting the analysed alignment between pk 102+500 and 106 (with sliding orientation towards East and North-East). The landslides are significant and very old. The main cause of occurrence of these landslides is the tectonic nature of the area. The two main landslides occur on large surfaces. Generally, the sliding plan is under the „fissure clay” level, so it tends to be 12 to15 m deep. Numerous reactivations occur within their congestion, on narrow or large surfaces. Many of the reactivations occur due to the malfunctions of the systems of rainfall draining and taking over from the national road that runs South to North on the Southern slope of the mountain Paduchiosu. There are no underground waters, but considering the change of the natural water drainage due to the existing road works, there are areas where the drainage is impeded or slowed, leading to the water infiltration and rocks moistening under the deluvial formation. The local reactivations may also be influenced by the unarranged torrential valleys. The project of rehabilitation of DN 71 is strongly influenced by existence of these significant landslides. Acknowledgement of the risk of landslide and allocation of funds for maintenance and remedial of the arisen damages following reactivations, as well as monitorization of the road areas affected by the landslides both during the works and after their completion, during operation, is the rightest solution, and actually, the least expensive one.

Controlling Surface Morphology and Circumventing Secondary Phase Formation in Non-polar m-GaN by Tuning Nitrogen Activity

For the development of non-polar nitrides based optoelectronic devices, high-quality films with smooth surfaces, free of defects or clusters, are critical. In this work, the mechanisms governing the topography and single phase epitaxy of non-polar m-plane gallium nitride (m-GaN) thin films are studied. The samples were grown using plasma-assisted molecular beam epitaxy on m-plane sapphire substrates. Growth of pure m-GaN thin films, concomitant with smooth surfaces is possible at low radio frequency powers and high growth temperatures as judged by the high resolution x-ray diffraction, field emission scanning electron microscopy, and atomic force microscopy measurements. Defect types and densities are quantified using transmission electron microscopy, while Raman spectroscopy was used to analyze the in-plane stress in the thin films which matches the lattice mismatch analysis. Energy dispersive spectroscopy and cathodoluminescence support a congruent growth and a dominant near band edge emission. From the analysis, a narrow growth window is discovered wherein epitaxial growth of pure m-plane GaN samples free of secondary phases with narrow rocking curves and considerable smooth surfaces are successfully demonstrated.

Experimental study of low pressure pool boiling of water from narrow tunnel surfaces

This article aims at studying pool boiling of water at sub-atmospheric pressure which takes place on narrow tunnel structures (NTS). This kind of surface consists of multiple horizontal and vertical channels that can remain open, or be covered with perforated copper foil. The structures were immersed under 5, 28.7, and 86.2 mm of distilled water. The range of saturation pressure range was 0.75–4 kPa (corresponding to a temperature range of 2.8–28.9 °C), and that of imposed heat flux was 0.25–3 W/cm2. The process of bubble creation and detachment, the bubble departure diameters and the frequencies were analyzed for three different NTS structures. Visual observations were complemented by measurements of temperatures and pressures, which were used to determine heat flux, superheat, and heat transfer coefficients.The boiling curves at sub-atmospheric pressure were shifted towards higher superheats in comparison to atmospheric pressure (this in agreement with the literature). NTS surfaces reduced this negative effect. Indeed, the NTS structures enhanced with perforated copper foil substantially improved heat transfer at low pressures, i.e. they increased the heat transfer coefficient and the bubble departure frequency.

Envisat RA-2 Individual Echoes: A Unique Dataset for a Better Understanding of Inland Water Altimetry Potentialities

The exploitation of synthetic aperture properties in nadir-looking radars is opening new scenarios in the framework of satellite radar altimetry. Both recent and upcoming missions including Cryosat-2, Sentinel-3, Sentinel-6 and SWOT take benefit from the coherent processing of radar data, aimed at improving range measurements in particular contexts, such as ice, open ocean, coastal zone, and even inland waters. This work investigates the possibilities offered by current and future satellite radar altimetry missions for the study of inland water bodies, probing into the peculiarities of the expected radar returns and their potential usage. In this regard, signals collected by the RA-2 instrument (Radar Altimeter 2) onboard the Envisat mission offer an unprecedented possibility, even with a relatively low pulse repetition frequency, to analyze the peculiarities of actual signals for detecting and ranging small water surfaces. In particular, the RA-2 instrument offers a global archive of Individual Echoes (IEs), collected at the native sampling rate of 1795 Hz, in addition to the 18 Hz data obtained by incoherent averaging, which are typically delivered to the users as standard products. RA-2 shares with future radar platforms such as Sentinel-6 a continuous and interleaved working modality, as was recommended by the scientific community in designing next missions’ requirements. This is a further reason to consider the usage of RA-2 IEs as particularly attractive. Whilst only available for a small percentage of the earth’s surface, sufficient IE data exist to study the height retrieval capability of these echoes, in particular for what concerns small water bodies, where we show that enough coherence is exhibited for focusing relatively narrow surfaces and range them correctly. A peculiar aspect of this work lies in the assumption that most of the returned echoes (in RA-2 IEs) are specular. A theoretical framework is developed according to this assumption, which is validated by investigating real RA-2 data and observing their related specular features. In particular, we discuss how specular echoes are expected to be very common in inland altimetry, and are most often associated with small to medium size lakes and rivers. This paper illustrates the expected electromagnetic behavior of specular water targets by exploiting the classical radar cross-section (RCS) theory for specular surfaces. Results from the model are compared with real IE data in three selected case studies, regarding two rivers of variable width and one flood plain, in order to check different hydrological regimes. The model very closely matches the data in all cases, making the results of this validation activity very promising. In particular, we demonstrate the feasibility of using satellite radar altimetry in rivers much smaller than what was considered possible until now.

(Invited) Electrochemistry 4.0

Manufacturing industry is currently at the dawn of a new industrial revolution. Within the past two centuries, humanity passed through three industrial revolutions leading us to the ability to mass produce complex products in affordable ways. However, manufacturing industry lost a significant element in this journey: individuality. Today’s customer is part of a global society in which connectivity and access to information plays a key role. As such a customer wants to be part of the world but in a very personal way, for example through unique and personal products. Industry recognized this new trend. Novel business models emerged. New key words are: cloud services, smart manufacturing, mass personalization. However, this results in a new challenge for manufacturing industry. Instead of mass fabricated products small series (batch-size 1) are required. Individual products can be fabricated by rapid-prototyping, but it is very challenging to produce personalized products in an economical way. New processes need to be developed which are of a new kind. This new revolution was recognized recently by industry and in Germany the key word industry 4.0 was introduced to characterize this “fourth industrial revolution”. The aim of industry 4.0 is to design smart factories in which batch-size 1 products on demand can be produced economically. This means that any cost not directly related to the final product must be reduced to zero. In mass production such indirect cost could be removed by spreading them over the immense number of identical fabricated products. In batch-size 1 production this is no longer possible, eliminating processes which require expensive tooling. Manufacturing processes must further be able to adapt themselves quickly and show a very high flexibility. Even process optimization becomes a real challenge. Among these challenges post-processing technologies take a prominent place. Manufacturing of a product is never achieved in a single step, even upon using technologies as additive manufacturing (AM). AM parts require post-processing in terms of surface finish. However, as printed parts are generally complex (much more complex parts can be produced by AM, reducing needs for assembly, driving costs down) methods for surface finishing become difficult to identify. AM Parts with narrow inner surfaces (dimensions < 1 mm) are particularly challenging to post-process. Currently few processes exist, which are all very labor intensive. Electro-polishing (EP) is a promising approach to tackle these issues. These considerations show that suitable manufacturing processes for batch-size 1 production must be highly flexible and have little overhead (in particular the need for tooling). As such, electrochemical processes are very promising. Such processes require little to no specialized tooling and are able to handle virtually any shape, including inner surfaces. In the present communication, it is shown how electrochemical processes can be used to design new manufacturing processes for industry 4.0. Some examples are discussed in the field of hard to machine materials and surface functionalization, and post-processing technologies as EP are discussed in more depth with experimental setup, parameter settings and used geometries. Titanium alloy (Ti6Al4V) AM parts (landing gear bracket) with surface roughness from Ra 13.9 µm | Rz 50.42 µm are successfully polished down to Ra 1.8 µm | Rz 6.26 µm with EP technology (see figure). Figure 1

Vibration Characteristics of Filter Capacitors Used in HVDC Converter Stations

Audible noise of can-type filter capacitors in high- voltage direct current converter stations originates from the vibration of capacitor cases, so it is meaningful to investigate the vibration characteristics. However, no experiment under practical excitations or thorough theoretical analysis was presented for the vibration characteristics. This study theoretically and experimentally investigated the vibration characteristics of can-type filter capacitors with stacked elements parallel to bottom. The vibration amplitude was found to be proportional to voltage squared. If the frequency spectrum of excitation voltage included several harmonics (more than three), vibration amplitude on some specific frequencies was related with the phases of these voltage components. Each capacitor surface had a concavo-convex vibration shape and the vibration of the bottom surface and the side surfaces were in opposite phases. The vibration amplitude of the bottom surface was the largest. Moreover, frequency characteristics of capacitor vibration were studied. The frequency response of the bottom surface was bigger than that of narrow and broad side surfaces for lower frequencies, while was smaller for higher frequencies. It was inferred that bottom surface vibration was mainly caused by elastic forces from direct contact and side surfaces vibration mainly came from damping forces from dielectric liquids.

Analysis of Glenoid Inter-anchor Distance with an All-Suture Anchor System

Objectives:Arthroscopic shoulder stabilization using suture anchors are commonly used techniques. More recently developed all-suture systems employ smaller diameter anchors, which increase repair contact area and allow greater placement density on narrow surfaces such as the glenoid. Our goal is investigate the strength characteristics of various inter-anchor distances in a human glenoid model.Methods:Twelve fresh-frozen human cadaveric glenoids were potted after the labrum was excised. The glenoids were then implanted with 1.4 mm all-suture anchors (Juggerknot, Biomet, Warsaw, IN) at varying inter-anchor distances. Anchors were implanted adjacent to one another or at 2 mm, 3 mm, or 5 mm distances using a template with pre-drilled holes. The glenoids were then underwent single cycle pullout testing using a test frame (Instron 8521, Instron Inc., Norwood, MA). A 5 N preload was applied to the construct and the actuator was driven away from the shoulder at a rate of 12.5mm/s as seen in Figure 1. Force and displacement were collected from the test frame actuator at a rate of 500 Hz. The primary outcomes were failure strength and stiffness. Stiffness was calculated from the initial linear region of the force displacement curve. Failure strength was defined as the first local maximum inflection point in the force displacement curve.Results:During load to fail testing, all but three of the specimens had both anchors pull out of the glenoid. The other mode of failure included one or both of the sutures failing. Stiffness was 13.52 ± 3.8, 17.97 ± 5.02, 17.59 ± 4.65 and 18.95 ± 4.67 N/mm for the adjacent, 2 mm, 3 mm and 5 mm treatment groups as shown Table 1. The adjacent group had a significantly lower stiffness compared to the other treatment groups. Failure strength was 48.68 ± 20.64, 76.16 ± 23.78, 73.19 ± 35.83 and 87.04 ± 34.67 N for the adjacent, 2 mm, 3 mm and 5 mm treatment groups as shown in Table 1. The adjacent group had a significantly lower failure strength compared to the other treatment groups.Conclusion:These data provide biomechanical evidence that in the glenoid, small diameter all-suture anchors may be implanted as close as 2 mm to one another without significantly decreasing their strength characteristics.

Integrating gastrocnemius force-length properties, in vivo activation and operating lengths reveals how Anolis deal with ecological challenges.

A central question in biology is how animals successfully behave under complex natural conditions. Although changes in locomotor behaviour, motor control and force production in relation to incline are commonly examined, a wide range of other factors, including a range of perch diameters, pervades arboreal habitats. Moving on different substrate diameters requires considerable alteration of body and limb posture, probably causing significant shifts in the lengths of the muscle-tendon units powering locomotion. Thus, how substrate shape impacts in vivo muscle function remains an important but neglected question in ecophysiology. Here, we used high-speed videography, electromyography, in situ contractile experiments and morphology to examine gastrocnemius muscle function during arboreal locomotion in the Cuban knight anole, Anolis equestris The gastrocnemius contributes more to the propulsive effort on broad surfaces than on narrow surfaces. Surprisingly, substrate inclination affected the relationship between the maximum potential force and fibre recruitment; the trade-off that was present between these variables on horizontal surfaces became a positive relationship on inclined surfaces. Finally, the biarticular nature of the gastrocnemius allows it to generate force isometrically, regardless of substrate diameter and incline, despite the fact that the tendons are incapable of stretching during cyclical locomotion. Our results emphasize the importance of considering ecology and muscle function together, and the necessity of examining both mechanical and physiological properties of muscles to understand how animals move in their environment.

Structural evolution and deformation kinematics of a subduction-related serpentinite-matrix mélange, Santa Elena peninsula, northwest Costa Rica

Detailed structural analysis of the Isla Pelada serpentinite-matrix mélange on Santa Elena Peninsula, Pacific coast of northwest Costa Rica, elucidates for the spatial distribution and temporal progression of a décollement-related deformation. This décollement zone constitutes the fault rock of a plate boundary in a subduction to collision setting. The décollement zone is defined by a thick tectonic mélange that includes blocks and belts of polymictic breccia, turbiditic greywacke, argillite, radiolarite, basalt, gabbro and serpentinized peridotite in a variably foliated serpentinite matrix. The chemical-mineral data of the peridotite blocks in the mélange indicate that they are fragments of abyssal mantle, different of the very depleted forearc mantle peridotites of the overlying Santa Elena ultramafic nappe.The structural evolution of the mélange can be divided into four main events. Early D1 deformation took place during underthrusting in the footwall of the décollement and is characterized by subhorizontal layer-parallel extension and subsequent by heterogeneous shearing of trench-fill deposits, oceanic volcanic rocks and variably serpentinized peridotites, resulting asymmetric boudinage, mesoscopic porphyroclasts and pervasive (S1) S–C fabrics. D1 is followed by layer-parallel contraction with early D2 folding and local development of an S2 pressure-solution cleavage, and late-D2 thrusting and large-scale duplexing. Therefore, D2 deformation evolves from pervasive coaxial subhorizontal contraction to a more localized non-coaxial strain (along relatively narrow thrust surfaces, in the mélange). D2 deformation mainly occurred in the hanging-wall of the décollement and was related to the downward migration of the subduction thrust. The result is the incorporation of slices of the subducted sequence by underplating into the overriding plate, typical of accretionary prisms.Kinematic indicators in the mélange are consistent with a general eastward-directed shearing during D1 and D2 deformations. This kinematics can be correlated with the direction of emplacement of the overlying Santa Elena ultramafic nappe during the early Upper Cretaceous. This also suggests the western-directed subduction of the oceanic lower plate. After the mélange was incorporated into the accretionary prism, the whole tectonic edifice was deformed in pre-late Campanian time by WNW–ESE trending D3 cylindrical upright folding and S-directed D4 narrow brittle thrusting. The recorded evolution of deformation in rocks already lithified, combined with the exotic origin of the oceanic lithologies and the serpentinite nature of the matrix points to disruption and mélange formation mainly during tectonic burial and underthrusting. In this context, the serpentinite matrix of the mélange is the result of the low-T hydration, metamorphism and deformation of mantle peridotites in a relatively shallow subduction setting.

Negative Pressures in Modelling Rotating Polymer Processing Machinery Are Meaningless, But They Are Telling Something

Abstract In the technical literature, some authors have reported calculation of negative pressures in simulations of twin screw extrusion and other types of processing, without giving any explanations. In the majority publications there is no mention of such meaningless results, even though theoretical considerations indicate that negative pressures could be obtained in the expansion region of drag flows through narrow non-parallel surfaces. The meaningless negative pressures are due to the application of single fluid theory to flow regions where bubbles would form, when the pressure drops below the vapor pressure of the liquid. This has been known for a long time from the study of lubrication bearings and related cavitation phenomena. It is argued that the boundary conditions should be carefully chosen for avoiding results in numerical simulations, which can never be reconciled with experimental pressure data.

Surface and bulk entanglement in free-fermion chains

We consider free-fermion chains where full and empty parts are connected by a transition region with narrow surfaces. This can be caused by a linear potential or by time evolution from a step-like initial state. Entanglement spectra, entanglement entropies and fluctuations are determined for subsystems either in the surface region or extending into the bulk. In all cases there is logarithmic behaviour in the subsystem size, but the prefactors in the surface differ from those in the bulk by 3/2. A previous fluctuation result is corrected and a general scaling formula is inferred from the data.

Numerical Simulation of Air Gap Formation in Water-Cooled Mold Casting

While using water cooled mold to produce steel ingot, an air gap is generated between the ingot and the mold, which has an important influence on the ingot quality. The air gap formation law and its influence on the solidification process were calculated by used FE software Procast. It is shown that, air gap occurs in a few minutes after the solidification begins. In 75-100s later the gap reaches 0.2-0.5 mm and starts to influent the heat transport significantly, the rate of the temperature decrease becomes slower. When the solidification is finished, there is a lager gap on the two narrow surfaces than it on the other wide surfaces; and the gap on the two narrow surfaces is different. The air gap on the narrow surface close to the sprue has a width of 12-20 mm; on the other narrow surface away from the sprue has a width of 4-13 mm. The biggest gap on the two wide surfaces has a size about 6.5mm. For the air gap is formatted between the ingot shell and the ingot mold, the solidification time is 50% longer than that of without air gap.