Parallel To Surface Research Articles

Banana leaves water extracts as inhibitor for X70 steel corrosion in HCl medium

In this work, we used experimental and theoretical calculation methods to investigate the corrosion inhibition nature of banana leaves water extract (BLWE) for X70 steel at 1 mol/L hydrochloric acid environment. The data of electrochemical tests manifest that the hydrochloric acid medium will accelerate the corrosion of X70 steel with increasing temperature. The charge transfer resistance dropped sharply from 55 Ω cm2 at 298 K to 18.4 Ω cm2 at 313 K. After adding BLWE in hydrochloric acid solution, the anti-corrosion efficiency of banana leaves extract for X70 steel can be maintained at about 90%. BLWE can simultaneously inhibit the anodic and cathodic reactions of X70 steel in hydrochloric acid solution, so it is mixed-type inhibitor. Surface morphology analysis strongly shows that BLWE can effectually restrain the corrosion of X70 steel. BLWE adsorption at the X70 steel surface is accord with Langmuir single-deck adsorption. Quantum chemical (QC) calculation and molecular dynamics simulations (MDS) have shown that (S)-2-amino-3-(4-hydroxyphenyl)propanoic acid (AHP), 3-(2-aminoethyl)-1H-indol-5-ol (ATI), and 3,4-Dihydroxycinnamic Acid (DDA) in BLWE can show excellent anti-corrosion character. QC calculation results show that AHP, ATI and DDA have small dipole moment values. The small dipole moment value is favorable the accumulation of inhibitor molecule on the X70 steel surface, thereby forming a denser barrier film. MDS results show that AHP, ATI and DDA can be adsorbed on the Fe (110) surface in parallel to obtain the maximum coverage.

Microstructural studies of direct-laser-deposited stainless steel 316L-Si on 316L base material

Microstructure and hardness of SS316L-Si deposited by direct laser deposition (DLD) on a conventional SS316L base material are studied. The DLD process produced a crack-free metallic part with a density of ~ 99.5%. The as-deposited samples exhibit a microstructure with millimetre-sized solidified melt pools. They consist mainly of columnar dendrites which were formed preferentially along direction, generating solidification texture and columnar grains. Dendrites with cellular morphology were also formed in regions of higher solidification rates, mainly above the localized heat-affected zone in the layers. The deposited SS316L-Si contains a primary austenitic matrix and secondary δ-ferrite in the interdendritic regions. The average hardness measured along parallel and normal surfaces with respect to the building direction is nearly the same (~ 185 HV), indicating homogeneity in the microstructure of the as-deposited SS316L-Si along the two orthogonal surfaces. The analysis of microstructure, defects and intermetallic phases was carried out using optical microscopy, scanning electron microscopy and transmission electron microscopy.

Application of horizontal wells in three-dimensional shale reservoir modeling: A case study of Longmaxi–Wufeng shale in Fuling gas field, Sichuan Basin: Reply

Three-dimensional reservoir modeling is an important aspect to determine the heterogeneity of organic-rich shale reservoirs, an area of study that continues to be explored and refined. A large proportion of data acquired from horizontal wells causes issues in the structural and property modeling for shale reservoirs. Since horizontal wells are designed to drill into a specific, narrow zone, their horizontal section tends to parallel or nearly parallel formation surfaces. As a result, formation surfaces have a much more complex spatial location relationship with horizontal wellbores than with vertical wellbores. The existing algorithms are not good at addressing this issue during structural modeling. The major problem of using horizontal well data in property modeling is the biased data set because their horizontal section tends to stay within a narrow zone. The property distribution feature estimated from this biased data set, as a significant, default input of geostatistical simulation algorithms, causes the constructed property models to deviate away from the real case in the subsurface. A method to infer more formation tops in pseudovertical wells according to a series of assumptions was developed to provide more constraint points for structural modeling within the areas of the horizontal well section. To use the biased database from horizontal wells, distribution function and trend model methods were developed for continuous property modeling, and percentage and probability trend models were developed for discrete property modeling. The Longmaxi–Wufeng shale in the Fuling gas field of Sichuan Basin was used as an example to express and verify these methods.

A modelling resin material and its application in rock-failure study: Samples with two 3D internal fracture surfaces

Abstract The mechanism of fracture propagation, interaction and coalescence inside rock masses is a highly concerned issue in geotechnical engineering. But as it is difficult to manufacture 3D internal pre-fractures and observe directly the failure evolution process inside real rocks or their opaque similar materials, most previous studies have been limited to 2D conditions. The experiment investigation on 3D rock failure is still in a preliminary stage. In this study, a resin material has been developed by extensive formula tries. It is absolutely transparent and the ratio of tension–compression strength (brittleness value) can be 1/6.6 at −10 to −15℃. It is much more brittle and rock-like than analogous materials used by former scholars. A set of preparation, casting mould, and post-processing technologies were established and specimen-making with multiple pre-fractures is enabled. In the designed scheme, specimens are made with two parallel internal fracture surfaces yet of four different stagger separations. Uniaxial tests were carried out and the stress–strain relationship is analysed. It is shown that the specimen has gone through four stages as the traditional rock test before failure. Many diverse forms of secondary fractures, such as wrapping wing crack, petaloid crack, and giant quasi-wrapping fracture surface, which were not found in 2D conditions have appeared and their evolutions were clearly seen in each stage.

Interactions between Colloidal Particles Mediated by Nonadsorbing Polymers: Casimir and Anti-Casimir Effects

We examined a simple model system of homopolymer solutions in 3D confined between two parallel and nonabsorbing surfaces and in equilibrium with a bulk solution and accurately calculated the effective interaction between the two surfaces using both lattice Monte Carlo (MC) simulations and self-consistent field (SCF) calculations. Our results here, when compared with those in 2D (Zhang, P.; Wang, Q., Macromolecules 2019, 52, 5777), quantitatively revealed that the fluctuation-induced intermediate-range repulsion between the two surfaces (i.e., the anti-Casimir effect) is about 1 order of magnitude stronger than the repulsion due solely to the finite chain length given by the SCF theory, is weaker but occurs over a broader range of surface separation in 3D than in 2D, and decreases with decreasing solvent quality. We also found for the first time a long-range attraction between the two surfaces (i.e., the Casimir effect) near the critical point of the bulk solution in both MC simulations and SCF calculations.

Silicon Direct Bonding for the European Space Agency's Next X-ray Observatory

Silicon direct bonding is a manufacturing process that is used in the fabrication of electronic, optical and mechanical microsystems. The chemical bonds are providing an intimate surface contact and strong structural stiffness that is for this reason also suitable for large assemblies. Together with the knowledge of the surface properties and of X-ray optics, we are making mirror imaging systems.The manufacturing process resorts to the highest-grade 12 inch silicon wafers with double Super Polished and near perfect plan parallel surfaces. With readily available semiconductor manufacturing and lithographic tools the wafers are processed into mirror plates with micrometer accuracy channel structures, yet maintaining the nanometer accurate figure of the silicon wafer. Multiple channeled X-ray mirrors shall subsequently be curved and stacked to form an optical component.We want to use such optical components for a ~3m diameter segmented optical system that would be part of the Athena observatory, European Space Agency's (ESA) next L-class mission, scheduled to launch in 2032. Athena will observe the hot and energetic Universe and answer two big scientific questions: How does ordinary matter assemble into the large-scale structures we see today? and how do black holes grow and shape the Universe?The scientific objectives of Athena require the largest X-ray optic ever flown. Silicon Pore Optics (SPO) is the selected technology that produces the building blocks for Athena's modular mirror. The segmented Athena optic will be made of about 700 X-ray mirror modules all co-aligned to a common focus, with radii of curvature varying from 0.25 m to 1.25 m. Furthermore, SPO has also shown to be a versatile technology that can be further developed for gamma-ray optics, medical applications and for material research.While considerable progress has been made on the performance of the optic, we are also upscaling towards an automated production line including mirror manufacturing, coating, cleaning, stacking and stack integration into mirror modules. The complete production line features many metrology steps to ensure quality and high yield. From the start, the development process has looked not just at the production of a single sample of high quality but at all the processes eventually required for the production of a complete system, and this in an effort to ensure that issues (mechanical, thermal, environment, supply chain etc) are identified early and addressed in a manner compatible with the core goal of producing high quality optics.In this paper we will discuss the challenges and present solutions that we have addressed. Cleanliness assessment, and bond strength enhancement are for instance two current topics of active development.

Silicon Direct Bonding for the European Space Agency's Next X-ray Observatory

Silicon direct bonding is a manufacturing process used in the fabrication of electronic, optical and mechanical microsystems. Chemical bonds are providing an intimate surface contact and strong structural stiffness that is, for this reason, also suitable for large assemblies. Based on the knowledge of the surface properties and of X-ray optics, we are making mirror imaging systems. The manufacturing process resorts to the highest-grade 12 inch silicon wafers with double-sided super polished and nearly perfect plan parallel surfaces. With readily available semiconductor manufacturing and lithographic tools, the wafers are processed into mirror plates with micrometer accuracy channel structures, yet maintaining the nanometer accurate figure of the silicon wafer. Multiple channeled X-ray mirrors shall subsequently be curved and stacked to form an optical component. We want to use such optical components for a ~3 m diameter segmented optical system that would be part of the Athena observatory.

Cross-hatched groove influence on the load carrying capacity of parallel surfaces with random roughness

For parallel surfaces, i.e. the oil control ring, the micro-geometry completely determines the hydrodynamic lubrication (HL).The cross-hatched grooves provide a certain load carrying capacity (LCC) and the surface (plateau) roughness can be an additional source. This paper extends earlier work to numerically solve the hydrodynamic pressure and LCC of parallel surfaces with random roughness and/or grooves. The influence of the groove spacing, width and depth on the LCC is studied.Results show that the larger the groove spacing, the higher the LCC. Grooves generate a large part of the LCC when the plateau roughness is small. However, for rough surfaces, grooves decrease the LCC and the wider or the deeper the grooves, the larger the decrease of the LCC.

Ex-vivo Alzheimer's disease brain tissue investigation: a multiscale approach using 1060-nm swept source optical coherence tomography for a direct correlation to histology.

.Significance: Amyloid-beta () plaques are pathological protein deposits formed in the brain of Alzheimer’s disease (AD) patients upon disease progression. Further research is needed to elucidate the complex underlying mechanisms involved in their formation using label-free, tissue preserving, and volumetric techniques.Aim: The aim is to achieve a one-to-one correlation of optical coherence tomography (OCT) data to histological micrographs of brain tissue using 1060-nm swept source OCT.Approach: plaques were investigated in ex-vivo AD brain tissue using OCT with the capability of switching between two magnifications. For the exact correlation to histology, a 3D-printed tool was designed to generate samples with parallel flat surfaces. Large field-of-view (FoV) and sequentially high-resolution volumes at different locations were acquired. The large FoV served to align the OCT to histology images; the high-resolution images were used to visualize fine details.Results: The instrument and the presented method enabled an accurate correlation of histological micrographs with OCT data. plaques were identified as hyperscattering features in both FoV OCT modalities. The plaques identified in volumetric OCT data were in good agreement with immunohistochemically derived micrographs.Conclusion: OCT combined with the 3D-printed tool is a promising approach for label-free, nondestructive, volumetric, and fast tissue analysis.

Correlation function approach for diffusion in confined geometries.

This paper describes a formalism for extracting spatially varying transport coefficients from simulations of a molecular fluid in a nanochannel. This approach is applied to self-diffusion of a Lennard-Jones fluid confined between two parallel surfaces. A numerical grid is laid over the domain confining the fluid, and fluid properties are projected onto the grid cells. The time correlation functions between properties in different grid cells are calculated and can be used as the basis for a fitting procedure for extracting spatially varying diffusion coefficients from the simulation. Results for the Lennard-Jones system show that transport behavior varies sharply near the liquid-solid boundary and that the changes depend on the details of the liquid-solid interaction. A quantitative difference between the reduced and detailed models is discussed. It is found that the difference could be associated with assumptions about the form of the transport equations at molecular scales in lieu of problems with the method itself. The study suggests that this approach to fitting molecular simulations to continuum equations may guide the development of appropriate coarse-grained equations to model transport phenomena at nanometer scales.

Experimental and Numerical Study of Jet Impingement Cooling for Improved Gas Turbine Blade Internal Cooling With In-Line and Staggered Nozzle Arrays

Abstract Internal cooling of gas turbine blades is performed with the combination of impingement cooling and serpentine channels. Besides gas turbine blades, the other turbine components such as turbine guide vanes, rotor disks, and combustor wall can be cooled using jet impingement cooling. This study is focused on jet impingement cooling, in order to optimize the coolant flow, and provide the maximum amount of cooling using the minimum amount of coolant. The study compares between different nozzle configurations (in-line and staggered), two different Reynold's numbers (1500 and 2000), and different stand-off distances (Z/D) both experimentally and numerically. The Z/D considered are 3, 5, and 8. In jet impingement cooling, the jet of fluid strikes perpendicular to the target surface to be cooled with high velocity to dissipate the heat. The target surface is heated up by a direct current (DC) power source. The experimental results are obtained by means of thermal image processing of the captured infra-red (IR) thermal images of the target surface. Computational fluid dynamics (CFD) analysis were employed to predict the complex heat transfer and flow phenomena, primarily the line-averaged and area-averaged Nusselt number and the cross-flow effects. In the current investigation, the flow is confined along with the nozzle plate and two parallel surfaces forming a bi-directional channel (bi-directional exit). The results show a comparison between heat transfer enhancement with in-line and staggered nozzle arrays. It is observed that the peaks of the line-averaged Nusselt number (Nu) become less as the stand-off distance (Z/D) increases. It is also observed that the fluctuations in the stagnation heat transfer are caused by the impingement of the primary vortices originating from the jet nozzle exit.

Non-lightlike constant angle ruled surfaces in Minkowski 3-space

In this paper, non-lightlike ruled surfaces of constant slope in Minkowski 3-space with a non-lightlike base curve c(s)=∫αt+βn+γbds, where t, n, b are tangent, principal normal and binormal vectors of an arbitrary timelike curve Γ(s) are investigated. Non-lightlike ruled surfaces of constant slope parallel to a tangent of a timelike general helix and normal of timelike slant helix are studied. It is shown that all non-lightlike ruled surfaces of constant slope are developable but not minimal surfaces.

Self-Assembly of Amphiphilic Janus Particles Confined between Two Solid Surfaces

We use Monte Carlo simulations to investigate the behavior of Janus spheres confined between two parallel surfaces. Janus particles are composed of attractive and repulsive parts. The slits with id...

Two-phase piecewise homogeneous plane deformations of a fibre-reinforced neo-Hookean material with application to fibre kinking and splitting

Two-phase piecewise homogeneous plane deformations are examined in respect of a neo-Hookean matrix material reinforced with embedded aligned fibres characterized by a single stiffness parameter. The deformations are interpreted in terms of fibre kinking and fibre splitting. Previous work has shown that such a transversely isotropic material can lose ellipticity if the reinforcing stiffness is sufficiently large and the fibre direction is sufficiently compressed. In particular, it was shown that the associated failure modes are characterised by the emergence of weak surfaces of discontinuity that are normal to the fibre direction (the onset of fibre kinking) or parallel to the fibre direction (the onset of fibre splitting). Here, the analysis of strong surfaces of discontinuity, developing from weak ones, is studied. The considered model can give rise to piecewise smooth plane deformations separated by a plane stationary surface of discontinuity, interpreted as either kinking or splitting. Attention is restricted to (plane) deformations in which, on one side of the surface of discontinuity, the load axis is aligned with the fibre axis. Then the fibre stretch on this side of the discontinuity is a natural load parameter. The ellipticity status of the two-phase piecewise homogeneous plane deformations is shown to span all four possible ellipticity/non-ellipticity permutations. If both deformation states are elliptic, then a suitable intermediate deformation is shown to be non-elliptic. Moreover, it is shown that the mechanism is dissipative, and maximally dissipative quasi-static failure motion is examined in respect of both kinking and splitting. It follows that, firstly, surfaces of discontinuity perpendicular to the fibre direction, associated with fibre kinking, are nucleated followed by surfaces of discontinuity parallel to the fibre direction, associated with fibre splitting. With respect to kinking, such maximally dissipative kinks nucleate only in compression as weak surfaces of discontinuity, with the subsequent motion converting non-elliptic deformation to elliptic deformation.

Near-Field Thermal Radiation between Two Plates with Sub-10 nm Vacuum Separation.

Radiation greatly exceeding blackbody between two objects separated by microscale distances has attracted great interest. However, challenges in reaching such a small separation between two plates have so far prevented studies below a separation distance of about 25 nm. Here, we report a study of radiation enhancement in the near-field regime of less than 10 nm between two parallel plates. We make use of bulk, rigid plates to approach small separation distances without the adverse snap-in effect, develop embedded temperature sensors to allow near-zero separation, and employ advanced sensing method to level the plates and approach and maintain small separations. Our findings agree with theoretical predictions between parallel surfaces with separations down to 7 nm where an 18000 times enhancement in radiation between two quartz plates is observed. Our method can also be used to explore heat transfer between other materials and can possibly be extended to smaller separation gaps.

On the parallel surfaces of the non-developable surfaces

On the parallel surfaces of the non-developable surfaces

Study on mechanical properties and wellbore stability of deep brittle shale

As the drilling depth of shale's oil and gas wells increases worldwide, the problem of borehole collapse and instability becomes increasingly serious. Due to the high content of brittle minerals in deep shale, the complex situation of an underground collapse of a site is often manifested as borehole wall caving and falling. On the basis of the deep shale of China's Longmaxi formation, we developed a simulation experiment involving the complex loading mechanics of underground working conditions. The influence of loading and unloading confining pressure speeds and the sealing properties of drilling fluid on the mechanical properties of rock were analyzed. We established the dynamic changes in borehole formation, combining seepage and pore pressure, the effective stress field around the well, and a method of evaluating wellbore stability in deep shale gas horizontal wells. The results show that the deep shale of the Longmaxi formation has a high brittle mineral content and is prone to brittle fracturing along parallel bedding surfaces under downhole pressure. The effective liquid column pressure at the bottom of the wells change noticeably under different working conditions. Changes in bottom hole fluid column pressure are the cause of the complicated situation of well leakage and overflow in the horizontal sections of the Longmaxi formation. The effective support confining pressure of borehole wall rock differs with different tripping out speeds. The faster the tripping out is, the less the support confining pressure of the wellbore rock and the easier it is to induce the rock to break down along the bedding. The effective sealing property of drilling fluid also affects wellbore stability. A good sealing property of drilling fluid can improve the supporting effect of the fluid on borehole wall rock and improve its resistance strength. On the whole, the pressure of the bottom hole liquid column is effectively controlled during drilling in the Longmaxi formation; this can avoid complicated situations such as well leakage. The results of this study provide a theoretical basis for the study of wellbore stability in deep shale formations during the drilling process.

A self-regenerating air-laid paper wrapped ASA 3D cone-shaped Janus evaporator for efficient and stable solar desalination

Solar desalination is one of the most sustainable and effective techniques to solve the long-standing challenge of fresh water supply. However, most of the current solar evaporators are designed with the light absorbing surface in parallel with the water evaporating surface, which causes significant salt accumulation and stability issues. Herein, a facile but scalable approach is reported to build tree-inspired, cone-shaped 3D Janus evaporators by spatially isolating absorption surface and evaporation surface, which exhibit self-regenerating behavior and significantly extended durability. Such evaporators employ hydrophobic polymer-based inner cones as the light absorbing surface, which were fabricated via 3D printing and featured wavelike and porous surface texture, that provides remarkable solar harvesting and fast thermal response. The outer surface of the cone was wrapped with superabsorbent air-laid paper, which not only provides efficient water supply featuring a bottom-up thickness gradient for evaporation but also avoids salt accumulation directly on the evaporation surface. Overall, the rational structure design and material combination enable the evaporator feature excellent heat-localization, efficient interfacial evaporation and remarkable long-term stability. It exhibited a stable evaporation rate of 1.713 kg m–2 h−1 for 14 days to 3.5% artificial seawater (solar/dark conditions for 9/15 h per day), without measurable decay. Most importantly, both experiments and COMSOL Multiphysics calculations reveal that the evaporator could also gain extra heat from surroundings. This work could provide new insights on the design of practical devices for effective water purification to address the critical water shortages challenges.

ROBOTIC ARM WITH BIoT MACHINE LEARNING SYSTEM

In this work, we present a robotic arm assisted by a visual system to decide whether an object with different colors, parallel flat surfaces and other types of surfaces would be subject to be manipulated without a drop risk. This robotic arm is assisted with sensors such as temperature, humidity, artificial vision, etc. and monitored with a Blockchain Internet of Things (BIoT) expert system assistance, which is shared and accessed by the internet by the users. A prototype for industrial purpose is launched to start providing data for training the expert system, achieving in this way an expert system with machine learning. The variations derived from the identification of the reference points and the characteristics of the robotic arm are a limiting factor of the system, however, it was possible to correctly locate the robotic arm in the workspace to take the object and manipulate it using machine learning based on a BIoT expert system.

Hydrothermal synthesis of Ni-based metal organic frameworks/graphene oxide composites as supercapacitor electrode materials

Abstract