Parallel To Surface Research Articles

Modelling the Tuning of the Cooperativity in Spin Crossover Sandwiched Layers

AbstractThis work is devoted to the investigation of the influence of the embedding surfaces (substrates) on a spin crossover layer in the framework of a mechanoelastic model. We analyze how the properties of the spin crossover molecules (i. e. the thermal transition or the cluster spreading) situated inside a 2D layer are influenced by interactions between them and the inert molecules situated on two parallel surfaces, embedding the spin crossover layer. We conclude that the thermal transition is influenced both at the macroscopic scale (the shape and wdith of the hysteresis accompanying the thermal transition) and at the microscopic scale (formation of clusters) by the presence of epitaxial interactions with substrates. Equally, we analyse how the spin transition modulates the pressure exerted by the middle layer on the two substrates. The last part of the paper is devoted to the study of the possibility to induce the switching of molecules in the inner layer by heating the embedding surfaces.

An improved analytical solution on viscous dissipation effect in extended Stokes’ second problem in microchannel with isothermal boundaries

In this analytical study, the fluid motion within a microchannel is induced by the oscillation of one surface parallel to the other stationary surface, termed the extended Stokes’ problem. The novelty and research gap are acquiring the thermal effect of such motion due to the viscous dissipation or fluid friction, subject to symmetric isothermal boundary conditions. The study may shed light on the role of viscous dissipation in temperature rise in the synovial fluid of an artificial hip joint, or in the fluid layer of a mechanical bearing. The full exact analytical temperature field, until now, has been unsolved, as it involves unsteady flow with manipulation of a complicated velocity field. The assumptions in the model are one-dimensional, incompressible, laminar, Newtonian flow with constant properties in a microchannel. Through the methodology of partial differential equation analysis, the temperature field is obtained in terms of Brinkman number, Prandtl number and a dimensionless angular frequency, and results are verified with a reported numerical solution, for specified range of the variables. Results complement recent approximate solutions which are valid only for the limited condition of the dimensionless angular frequency being less than or equal to unity, whereby suggesting a new Stokes number.

Study on the Control of Steam Front Mobility in High-Temperature and High-Salinity Conditions Using Polymer-Enhanced Foam.

This study investigated the enhancing effects of the temperature-resistant polymer Poly(ethylene-co-N-methylbutenoyl carboxylate-co-styrenesulfonate-co-pyrrolidone) (hereinafter referred to as Z364) on the performance of cocamidopropyl hydroxy sulfobetaine (CHSB) foam under high-temperature and high-salinity conditions. The potential of this enhanced foam system for mobility control during heavy oil thermal recovery processes was also evaluated. Through a series of experiments, including foam stability tests, surface tension measurements, rheological assessments, and parallel core flooding experiments, we systematically analyzed the interaction between the Z364 polymer and CHSB surfactant on foam performance. The results indicated that the addition of Z364 significantly improved the strength, thermal resistance, and salt tolerance of CHSB foam. Furthermore, the adsorption of CHSB on the polymer chains enhanced the salt resistance of the polymer itself, particularly demonstrating stronger blocking effects in high-permeability cores. The experimental findings showed that Z364 increased the viscosity of the liquid film, slowed down liquid drainage, and reduced gas diffusion, effectively extending the half-life of CHSB foam and improving its stability under high-temperature conditions. Additionally, in parallel core flooding experiments, the polymer-enhanced foam exhibited significant flow diversion effects in both high-permeability and low-permeability cores, effectively directing more fluid into low-permeability channels and improving fluid distribution in heterogeneous reservoirs. Overall, Z364 polymer-enhanced CHSB foam demonstrated superior mobility control during heavy oil thermal recovery, offering new technical insights for improving the development efficiency of high-temperature, high-salinity reservoirs.

Quantitative analysis of heat and mass transfer in MoS2-Al2O3/EG hybrid flow between parallel surfaces with suction/injection by numerical modeling of HPM method

This description focuses on how the magnetic field affects mass and heat transfer in a hybrid nanofluid (Hnf) between two parallel, rotating plates. By dispersing aluminum oxide (Al2O3) and molybdenum disulfide (MoS2) nanoparticles (NPs) in ethylene glycol (EG), a hybrid nanofluid (Hnf) is created. This research aims to analyze the heat and mass transfer characteristics in the flow of a hybrid nanofluid (MoS2-Al2O3/EG) between two rotating parallel plates under the influence of a magnetic field. Furthermore, the statistical technique of response surface methodology (RSM) has been employed to optimize the parameters of velocity, temperature, and concentration of the nanofluid within the flow region bounded by the rotating plates. Dimensionless differential equations have been calculated and checked using the Homotopy perturbation method. This study introduces a novel approach by utilizing the RSM method to identify optimal points for velocity and temperature parameters of nanofluids between two stretching plates for the first time. Additionally, the article innovatively applies the exact HPM method to validate dimensionless linear and non-linear coupling equations. As the Reynolds number and the suction/injection coefficient of nanofluids flowing between two plates under tension increase, the results indicate a decrease in the velocity field. This decrease in velocity field can be attributed to the reduction in fluid diffusion as viscous forces diminish with varying Reynolds numbers. The ideal temperature distribution for nanofluids flowing between two parallel plates occurs when they are uniformly dispersed at the midpoint between them. As the distance from the initial point of nanofluid entry to the end of the plates increases, along with the vertical distance from the bottom plate, the temperature gradient diminishes, reducing the thickness of the thermal boundary layer. The velocity gradient and the rate of heat flux transfer between the nanofluid and plate rise by 34 % when the volume percentage is raised from 1 % to 5 %.

Water and Carbon Dioxide Capillary Bridges in Nanoscale Slit Pores: Effects of Temperature, Pressure, and Salt Concentration on the Water Contact Angle.

We perform molecular dynamics (MD) simulations of a nanoscale water capillary bridge (WCB) surrounded by carbon dioxide over a wide range of temperatures and pressures (T = 280-400 K and carbon dioxide pressures ≈ 0-80 MPa). The water-carbon dioxide system is confined by two parallel silica-based surfaces (hydroxylated β-cristobalite) separated by h = 5 nm. The aim of this work is to study the WCB contact angle (θc) as a function of T and . Our simulations indicate that θc varies weakly with temperature and pressure: Δθc ≈ 10-20° for increasing from ≈0 to 80 MPa (T = 320 K); Δθc ≈ -10° for T increasing from 320 to 360 K (with a fixed amount of carbon dioxide). Interestingly, at all conditions studied, a thin film of water (1-2 water layers-thick) forms under the carbon dioxide volume. Our MD simulations suggest that this is due to the enhanced ability of water, relative to carbon dioxide, to form hydrogen-bonds with the walls. We also study the effects of adding salt (NaCl) to the WCB and corresponding θc. It is found that at the salt concentrations studied (mole fractions xNa = xCl = 3.50, 9.81%), the NaCl forms a large crystallite within the WCB with the ions avoiding the water-carbon dioxide interface and the walls surface. This results in θc being insensitive to the presence of NaCl.

A note on parallel mean curvature surfaces and Codazzi operators

A note on parallel mean curvature surfaces and Codazzi operators

SPR based dual parameter wide range curling pot shaped photonic crystal fiber sensor

This article proposes a curling pot shaped photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR), which utilizes two parallel polished surfaces in the cladding to achieve dual parameter measurements of liquid refractive index (RI) and temperature. The mode characteristics and sensing performance of the designed PCF sensor are studied using the finite element method, and the effects of changes in structural parameters such as pore radius, spacing, and gold film thickness on the resonance spectrum are analyzed. The sensing accuracy of the sensor is insensitive to the change of structural parameters, and it has the characteristics of a wide detection range, high sensitivity, and easy manufacture. When the measured RI is in the range of 1.33∼1.42, the maximum RI sensitivity is 20400 nm RIU−1, and the maximum FOM is 483.3 RIU−1. When the temperature ranges from −10 °C to 100 °C, the maximum sensitivity is 15.4 nm °C−1, and the maximum FOM is 0.43 RIU−1. The tight structure design of the sensor core close to the polishing surface and the anti-spill light design with a uniform arrangement of air holes enhance the SPR effect, which is the essential reason for achieving a wide detection range and high sensitivity.

Numerical simulation of heat and mass transfer through hybrid nanofluid flow consists of polymer/CNT matrix nanocomposites across parallel sheets

The hybrid nanofluid (Hnf) flow with heat and mass transmission under the magnetic field and activation energy consequences across parallel double-rotating surfaces has been studied. In order to synthesize the Hnf, polymer/CNT matrix nanocomposites (MNCs) are dissolved in water. Polymer/CNT MNCs are highly efficient and have exceptional properties. These MNCs are helpful in various applications, from engineering to biomedical research, because of their incredible thermophysical properties. Keeping in view the significant uses of the polymer/CNT MNC hybrid nanofluid flow, we have formulated the fluid flow in the form of the system of PDEs (partial differential equations), which are reformed into the non-dimensional form of ODEs (ordinary differential equations) and then solved numerically through the Matlab package (bvp4c). The numerical outputs for velocity, heat and mass profiles are compared with another numerical approach ND-solve. It has been determined that the outputs are precisely correct and reliable. Furthermore, the fluid velocity drops with the influence of suction/injection, Reynold number, and polymer/CNT MNC. The increasing quantity of polymer/CNT MNC in water reduces the energy and mass profiles. The energy field enhances with the upshot of the heat source term, whereas the concentration field falloffs with the effect of Schmidt number.

Development of rare earth element and carbon fiber‐based filler for polyethylene—Mechanical and thermal performance

AbstractIn the present study, three fillers produced with carbon fiber powder (CFP) and rare earth elements were developed for low‐density polyethylene production. These fillers included CFP with a grain size of less than 400 microns and over 90% pure lanthanum and cerium oxides. Polyethylene was employed to ensure the thermoplasticity and homogeneity of the fillers. The fillers were mixed with the matrix material separately, first mechanically and then homogenously in the extruder, then the test bars were produced with an injection machine. In the mechanical tests, it was determined that the tensile strength of the test bars improved by ~20% and the elastic region increased due to the increasing amount of filler. Similarly, an improvement of about 40% in bending stress was realized. In addition, as the fluidity of the mixtures has improved, it has been possible to produce at lower temperatures and save energy in the production. Thermogravimetric analysis was conducted to determine the melting/crystallization temperatures and material losses in the compounds. The scanning electron microscope analysis showed that the fillers were irregularly distributed on the surface in parallel and perpendicular directions. In addition, x‐ray diffraction and energy dispersive spectroscopy analyses were performed on the surfaces.

Enhancement-mode Ga2O3 FETs with an unintentionally doped (001) β-Ga2O3 channel layer grown by metal-organic chemical vapor deposition

High-quality unintentionally doped (UID) (001) β-Ga2O3 homoepitaxial films were grown on native substrates through metalorganic CVD. The surface parallel grooves were repaired under low temperature and pressure conditions, reaching the surface roughness of 2.22 nm and the high electron mobility of 74.6 cm2/Vs. Enhancement-mode MOSFETs were fabricated on the UID β-Ga2O3 film, showing a positive turn-on threshold gate voltage of 4.2 V and a breakdown voltage of 673 V. These results can serve as a reference for (001)-oriented lateral Ga2O3 power transistors and may contribute to the development of Ga2O3 power devices.

Investigating the synergistic effect of iodide ion and Michelia alba leaf extract on carbon steel in 0.5 M H2SO4

The study examined the inhibitory effect of Michelia alba leaf extract (MALE) on carbon steel (CS) in 0.5 M H2SO4 solution. Furthermore, the investigation explored the effect of KI to enhance the protection provided by MALE. The study demonstrates that both MALE and KI have corrosion inhibiting properties on CS in acidic solutions. However, when MALE and KI are combined, they exhibit a greater inhibitory effect. Corrosion inhibition efficiency was limited to 86.55 % with 400 mg/L MALE. The maximum corrosion inhibition efficiency was 51.84 % when 400 mg/L KI was used alone. However, when 800 mg/L MALE was combined with 400 mg/L KI in 0.5 M H2SO4 solution, the efficiency increased to 95.02 %. This increase can be attributed to the synergistic effect between MALE and KI. The SEM and XPS results further confirmed that the addition of KI could be more effective in preventing the corrosion of CS. The theoretical calculations demonstrate that constituents found in the extract, which are rich in hydroxyl groups, benzene rings, N and S atoms have a higher probability of adsorption onto the CS surface in parallel, thereby increasing the efficiency of corrosion inhibition significantly.

A general element for shell analysis based on the scaled boundary finite element method

AbstractA novel technique, the scaling surface‐based Scaled Boundary Finite Element Method (SBFEM), is introduced as a method for formulating a general element for shell analysis. This displacement‐based element includes three translational degrees of freedom (DOFs) per node. Notably, only two‐dimensional discretization for one of the two parallel shell surfaces, referred to as the scaling surface, is necessary. The interpolation scheme for the scaling surface is postulated to be applicable to all surfaces parallel to it in the thickness. The derivation strictly adheres to the 3D theory of elasticity, without making additional kinematic assumptions. As a result, the displacement field along the thickness is analytically solved, and the element formulation is immune to transverse locking, membrane locking, and other issues, eliminating the need for additional remedies. Extensive investigations into the robustness and accuracy of the elements have been conducted using well‐known benchmark problems, along with additional challenging problems. Numerical examples confirm that the element formulation is free from transverse shear locking and membrane locking. Moreover, the proposed formulation is easily extendable to cases involving shell elements with varying thickness and holds the potential for extension to the nonlinear response analysis of shell structures.

Quantitative stability for overdetermined nonlocal problems with parallel surfaces and investigation of the stability exponents

In this article, we analyze the stability of the parallel surface problem for semilinear equations driven by the fractional Laplacian. We prove a quantitative stability result that goes beyond the one previously obtained in [15].Moreover, we discuss in detail several techniques and challenges in obtaining the optimal exponent in this stability result. In particular, this includes an upper bound on the exponent via an explicit computation involving a family of ellipsoids. We also sharply investigate a technique that was proposed in [14] to obtain the optimal stability exponent in the quantitative estimate for the nonlocal Alexandrov's soap bubble theorem, obtaining accurate estimates to be compared with a new, explicit example.

Parallel surfaces of the non-lightlike solution of vortex filament equations

Parallel surfaces of the non-lightlike solution of vortex filament equations

Experimental study of hydraulic fracturing for deep shale reservoir

Compared with shallow reservoirs of shale gas, the high stress and plasticity of shale reservoirs under deep conditions significantly impact the propagation of hydraulic fractures. The study investigates the characteristics of hydraulic fracture propagation in deep shale reservoirs by conducting true triaxial fracturing tests at different stress levels and combinations under circumstances close to the original in-situ stress of the target reservoir. Specifically, it includes comparative experiments under high and low-stress levels, variable stress combinations with equal stress differences, and experiments on the influence of maximum and minimum horizontal in-situ stress, respectively. Through a series of experimental studies, it has been shown that the fracture roughness is relatively low at high stress levels. Fractures can still generate complex and multiple fractures when subject to high-stress conditions. Amongst, natural fissures or weak surfaces still dominate the complex fracture morphology. In the case of a higher in-situ stress level with the same stress difference value brings about a more complex hydraulic fracture morphology as a result of a smaller stress-difference coefficient. The Intersection of hydraulic fractures with multiple parallel weak surfaces creates hydraulic fractures in stepped shape, which can cause drastic fluctuations in injection pressure. The research results provide a reference for on-site deep shale reservoir stimulation and optimization of a fracturing design.

Microscopic deformation mechanism and characteristics of carbonaceous slate during the creep process

Carbonaceous slate exhibits a significant creep deformation that seriously affects the construction and operation of underground projects. To investigate the microstructural changes characteristics and reveal the microscopic deformation mechanism of the carbonaceous slate during the creep process, multiple methods were performed, including the triaxial creep test, SEM and MIP. The following conclusions were drawn: The rock samples underwent three stages during the creep test: microporosity closure at a low-stress level, material densification at an intermediate stress level, and microcracks emerging and expanding to failure at the high stress. The creep deformation was particularly significant in the first and third processes. The lamellar particles are compressed or bent under stress in parallel and vertical directions, showing the anisotropic properties of deformation. The deformation of the rock sample is related to the angle between the bedding and the orientation of major principal stress, and the effect of the anisotropy decreases with the increased stress level. The sprouting and expansion of microfractures occur at high-stress levels, showing pressure dissolution of mineral particles, migration of very fine particles, and cement damage between lamellar particles. Finally, the horizontal samples formed a combined rupture surface composed of the laminar surface and the fracture surface intersecting it, showing brittle damage, while the vertical samples formed a fracture surface parallel to the laminar surface, showing a ductile damage pattern. Those results could provide the basis for a further understanding of the mechanical properties of carbonaceous slate and the improvement of its creep model and parameters. It was significant for the stability analysis and deformation prediction of engineering structures using numerical simulation.

Nonlinear analysis of laminated composite shells with piezoelectric patches under displacement‐dependent pressure loads

AbstractIn this paper, the three‐dimensional stress field in nonlinear laminated composite shells with piezoelectric patches subjected to displacement‐dependent loads is analyzed. To solve the problem, the geometrically exact (GeX) hybrid‐mixed four‐node solid‐shell element has been developed. The term GeX means that the middle surface is described by analytical functions, including spline functions, and, therefore, the coefficients of the first and second fundamental forms are taken exactly at the element nodes. The laminated solid‐shell element formulation is based on the choice of an arbitrary number of sampling surfaces (SaS) parallel to the middle surface and located at the Chebyshev polynomial nodes within the layers, in order to introduce the displacements and electric potentials of these surfaces as unknown functions. The outer surfaces and interfaces are also included into a set of SaS. Due to analytical integration utilized to evaluate the tangent stiffness matrix, the proposed GeX piezoelectric solid‐shell element under nonconservative loading exhibits superior performance in the case of coarse meshes and allows the use of only one load step in all considered benchmark problems. Therefore, it can be recommended for the large deformation analysis of doubly curved laminated composite shells with piezoelectric patches, since the SaS formulation allows one to find three‐dimensional solutions of electroelasticity with a prescribed accuracy.

An Optical Sensor for Measuring Displacement between Parallel Surfaces.

An optoelectronic sensor was developed to measure the in-plane displacement between two parallel surfaces. This sensor used a photodetector, which was placed on one of the parallel surfaces, to measure the intensity of the red (R), green (G), blue (B), and white/clear (C) light spectra of a broad-spectrum light that was reflected off a color grid on the opposing surface. The in-plane displacement between these two surfaces caused a change in the reflected RGB and C light intensity, allowing the prediction of the displacement direction and magnitude by using a polynomial regression prediction algorithm to convert the RGB and C light intensity to in-plane displacement. Results from benchtop experiments showed that the sensor can achieve accurate displacement predictions with a coefficient of determination R2 > 0.97, a root mean squared error (RMSE) < 0.3 mm, and a mean absolute error (MAE) < 0.36 mm. By measuring the in-plane displacement between two surfaces, this sensor can be applied to measure the shear of a flexible layer, such as a shoe's insole or the lining of a limb prosthesis. This sensor would allow slippage detection in wearable devices such as orthotics, prostheses, and footwear to quantify the overfitting or underfitting of these devices.

Extreme near-field heat transfer between silica surfaces

Despite recent experiments exhibiting an impressive enhancement in radiative heat flux between parallel planar silica surfaces with gap sizes of about 10 nm, the exploration of sub-nanometric gap distances remains unexplored. In this work, by employing non-equilibrium molecular dynamics (NEMD) simulations, we study the heat transfer between two SiO2 plates in both their amorphous and crystalline forms. When the gap size is 2 nm, we find that the heat transfer coefficient experiences a substantial ∼30-fold increase compared to the experimental value at the gap size of 10 nm confirming the dependence on the distance inversely quadratic as predicted by the fluctuational electrodynamics (FE) theory. Comparative analysis between NEMD and FE reveals a generally good agreement, particularly for amorphous silica. Spectral heat transfer analysis demonstrates the profound influence of gap size on heat transfer, with peaks corresponding to the resonances of dielectric function. Deviations from the fluctuational electrodynamics theory at smaller gap sizes are interpreted in the context of acoustic phonon tunneling and the effects of a gradient of permittivity close to the surfaces.

Study on the texture evolution and mechanical properties of selective laser melting pure nickel

As a ductile and ferromagnetic transition metal, nickel possesses exgrainent metallurgical compatibility, corrosion resistance, high electrical conductivity and high temperature stability. This study investigates the influence of energy density on the microstructure and properties of laser powder bed fusion pure nickel. The research results demonstrate that: during the formation process of Ni, with the increase in energy density, the grain texture exhibits anisotropy. The surfaces parallel and perpendicular to the building direction demonstrate strong {111} and {220} textures respectively. Primary and secondary recrystallization leads to increase in texture strength, subsequently affecting the decrease in dislocation density. The {111} texture yields preferentially, while the {220} single-crystal-like microstructure (SCM) requires higher energy density to complete primary recrystallization and trigger the recovery and enhancement of {111} texture. The enhancement in tensile properties is mainly attributed to the improvement of unmelted defects and texture. With the loading of stress, the failure of the structure leads to a decrease in the strength of the optimal texture component. The {220} texture strengthens the bond between different cladding layers along the building direction, resulting in numerous epitaxial grains parallel to the building direction on the fracture surface, significantly increasing the elongation of the specimen.