Layer Displacement Research Articles

Using 14C-Dated Peat Beds for Reconstructing Subsidence by Compression in the Holland Coastal Plain of the Netherlands

ABSTRACT Koster, K.; Cohen, K.M.; Stafleu, J., and Stouthamer, E., 2018. Using 14C-dated peat beds for reconstructing subsidence by compression in the Holland coastal plain of the Netherlands. Subsidence in the Holland coastal plain of the Netherlands was reconstructed from the vertical displacement of Holocene peat layers below their reference groundwater levels at the time of peat formation. This quantifies the part of subsidence that is due to compression processes and allows specification of the current state of peat compression in a map. 14C-dating of peat layers found intercalated in the Holocene sequence were used in the reconstruction. This dataset was combined with results from a recent coastal-deltaic plain wide three-dimensional (3D) interpolation of reference palaeo-groundwater levels, at which the intercalated peats are thought to have formed before they were buried, compressed, and vertically displaced. Empiric relations between reconstructed displacement and the thickness of overburden were...

Convective Boundary Layer Flow of Magnetic Nanofluids under the Influence of Geothermal Viscosity

The purpose of the present study is to examine the effects of geothermal viscosity on an unsteady flow of incompressible magnetic nanofluids (C1-20B & Taiho-W40) due to a heated rotating disk. The modeled system of nonlinear coupled partial differential equations governing the unsteady flow together with the two point variable boundary conditions have been transformed into the set of non-linear coupled ordinary differential equations. The resultant set of equations is then solved by fourth order Runge-Kutta method in MATLAB using ODE45 with shooting technique for initial guess. The influences of geothermal viscosity variations ( for temperature & for depth) along with the ferro-hydro-dynamic (FHD) interaction parameter and rotational parameter R on the flow and temperature field generated on the plate surface are elucidated. Besides the above profiles; effects of both, depth and temperature dependent viscosity parameters are also examined on the skin frictions, rate of heat transfer and boundary layer displacement thickness. The computed results for stronger (C1-20B) and weaker (Taiho-W40) convective magnetic nanofluids (MNF) have been discussed and compared vis-a-vis.

Evaluation of multiple transducers implementation in a magnetoelectric vibration energy harvester

Abstract A novel magnetoelectric (ME) vibration energy harvester employing magnetostrictive and piezoelectric laminate composite transducers is presented for potentially powering wireless sensor systems. The harvester consists of two four-layered Terfenol-D/PZT laminate composite and a magnetic circuit composed by two parallel magnetic springs and two rectangular magnets. The repulsive forces are realized by a magnetic spring for more robustness. In order to realize a high power density, a multiple transducer design with a lateral configuration is proposed. The magnetic flux density and the induced displacement in the magnetostrictive layers are investigated by finite element analysis to determine the optimal relative position of the twin transducers at the static equilibrium. Furthermore, the output characteristics of the harvester are experimentally studied and compared to the case when only a single transducer is used. The experimental results show that the twin lateral converter can provide a higher power outcome especially if operated at resonance. In addition, doubling the amplitude of vibration from 0.5 mm to 1 mm leads to a voltage output which is four times higher at resonance.

THE N.A. GOLOVKINSKY’S FUNDAMENTAL FACIAL LAW — PROBLEMATICS AND NEW HORIZONS

Famous Russian geologist N.A. Golovkinsky published 150 years ago an important scientific work, where the phenomenon of lateral displacement (movement) of homogeneous lithological layers («slide» over time) was asserted. This created the most significant prerequisites for the fundamental facial law: the layers, lying nearby, were formed in the same sequence vertically. The law was formulated a little later by A.A. Inostrantsev, and later «rediscovered» by J. Wal- ter. The ideas, developed by N.A. Golovkinsky, subsequently found the application in the study of geological cyclicity, and currently in the booming seismic stratigraphy. The creative improvement and continuation of theoretical positions contained in the Golovkinsky’s work allowed to advance a method of facially-cyclic analysis, which has been success- fully used in the study of many coal-bearing strata, and is currently used for coal-free deposits of the West Siberian oil and gas basin. Methodically, they develop an understanding of causality and correspond to the principles of synergetic world-view. The main content of these ideas remains relevant in the light of new realities of cognitive process (nonlin-ear science, endovision).

РЕЗУЛЬТАТЫ ИССЛЕДОВАНИЯ УПЛОТНЕНИЯ ДВИЖИТЕЛЯМИ ТРАКТОРОВ МЕЖДУРЯДЬЯ ХМЕЛЬНИКА

Based on experimental studies, a technique was proposed for comparing the areas of compaction by tractor propulsors in field conditions and in the aisle interval, the zones of inefficient and intensive use of the hopper space were determined and the solution of the problem of the optimization of the aisle zones was given. The results of experimental studies of the density of soil composition on hop crops are summarized in caterpillar compaction (LLC “Agrokhmel” of Vournarsky District, Chuvash Republic) and wheeled tractors (KOPKh “Leninskaya iskra” of Yadrinsky District, Chuvash Republic). In the first case, the T-54B tracked tractor was used, and in the second - the MTZ-921 wheeled tractor. The soils under the hops in LLC “Agrokhmel” are predominantly dark gray forest soils with an average humus content of 4.1% at a depth of 0.2 m, in KOPKh “Leninskaya iskra” - gray forest with a humus content of 2.9% (at a depth of 0, 2 m). According to the results of the implementation of soil sections on the hop-growers of the Chuvash Republic, it has been established that at the depth of the arable layer 0 ... 0.3 m there are no completely hop roots between traces of tractor passage. Analyzes of shear vertical deformation under the trail of the tractor’s wheel and its propagation along the depth show that after a threefold passage along the same trail, the displacement of soil layers practically ceases, while at the same time, in modern hone-growing technologies, up to 12 ... 14 passes intercoupling. To improve the conditions for growing hops, a quantitative reduction in the blocked zone of the hop-crop intervals is necessary. The study found that the density of the composition of the soil active hop under the tracks of the tractor T-54B is greater than under the wheel tractor MTZ-921. The resulted analytical decisions have shown that the zone of intensive usage of the hop-crop spacing more than 60% is achieved with the use of tractors T-54B and T-25A with the smallest rim when planting the hop sprocket with a spacing of 3.33 m.

Experimental study on seismic performance of Song-style Dou-gong joints in Chinese traditional building

Research on the mechanics performance of Song-style Dou-gong joints is absent currently, especially considering Xiaang and Angshuan in this type of joints. Two different types of Dou-gong joints were experimentally studied by making models in this paper. The Dou-gong joints can maintain good integrity and rotate around the bottom member in the longitudinal plane under horizontal loads, which shows poor seismic performance. The displacement of layers is less, Xiaang and Angshuan can limit slippage between components to some extent, but they had little effect on the seismic performance of the Dou-gong joints.

Cyclic Changes of the Sun’s Seismic Radius

Abstract The questions asking whether the Sun shrinks with the solar activity and what causes this have been a subject of debate. Helioseismology provides a means to measure with high precision the radial displacement of subsurface layers, the so-called “seismic radius,” through the analysis of oscillation frequencies of surface gravity (f) modes. Here, we present results of a new analysis of 21 years of helioseismology data from two space missions, the Solar and Heliospheric Observatory and the Solar Dynamics Observatory, which allow us to resolve previous uncertainties and compare variations of the seismic radius in two solar cycles. After removing the f-mode frequency changes associated with the surface activity, we find that the mean seismic radius is reduced by 1–2 km during the solar maxima and that most significant variations of the solar radius occur beneath the visible surface of the Sun at a depth of about 5 ± 2 Mm, where the radius is reduced by 5–8 km. These variations can be interpreted as changes in the solar subsurface structure caused by the predominately vertical ∼10 kG magnetic field.

Flow modulation by a mushroom-like coating around the separation region of a wind-turbine airfoil section

The flow over a mushroom-shaped microscale coating was experimentally inspected over a diverging channel that followed the pressure side of a wind turbine blade (S835). High-resolution particle image velocimetry was used to obtain in-plane velocity measurements in a refractive-index-matching flume at Reynolds number Reθ ≈ 1200 based on the momentum thickness. The results show that the evolution of the boundary layer thickness, displacement thickness, and shape factor change with the coating, contrary to the expected behavior of an adverse pressure gradient boundary layer over a canonical rough surface. Comparison of the flow with that over a smooth wall revealed that the turbulence production exhibited similar levels in both cases, suggesting that the coating does not behave like a typical rough wall, which increases the Reynolds stresses. Proper orthogonal decomposition was used to decompose the velocity field to investigate the possible structural changes introduced by the wall region. It suggests that large-scale motions in the wall region lead to high-momentum flow over the coated case compared to the smooth counterpart. This unique behavior of this surface coating can be useful in wind-turbine applications, with great potential to increase the power production.

The Efficiency of the Ability of Isolation Piles to Control the Deformation of Tunnels Adjacent to Excavations

There is a lack of research on the mechanisms by which isolation piles affect displacements in deep soil layers and the use of isolation piles to control the displacement and deformation of the existing tunnels adjacent to deep excavations. This paper examines a large, deep excavation project in which isolation piles were used to protect a nearby existing tunnel. A finite-element model that considers the small-strain characteristics of the soil was used to simulate this project. After the numerical model is verified, it is used in a parametric analysis of the mechanisms by which isolation piles control the displacement of deep soil layers and the deformation of tunnels near excavations. The results show that isolation piles have both a barrier effect and a traction effect on the surrounding soil and adjacent tunnels. When the traction effect is larger, isolation piles can exacerbate the horizontal displacement of the soil and tunnel within a certain depth range and actually increase tunnel deformation. Burying the isolation piles reduces this traction effect and improves their ability to isolate tunnels from displacement. All else being equal, isolation piles more efficiently control deformation if they are near the tunnel.

Effectiveness of fluid-viscous dampers for improved seismic performance of inter-storey isolated buildings

The use of fluid viscous dampers (FVDs) together with isolators, frequent in near-fault buildings, is effective in reducing displacements of the isolation layer. Such a hybrid system is also beneficial in the case of inter-storey isolation with the aim of limiting P-Δ effects. However, previous research on base isolation shows that this additional damping may also be detrimental, as inter-storey drifts and floor accelerations may increase.This paper analyses the effectiveness of FVDs for enhanced seismic performance of systems with inter-storey isolation. A seven-floor building, with natural and lead rubber bearings between the second and third levels, was used as a case study, and a multi-objective optimal design was performed to identify the best damper parameters. In particular, time-history analyses with various natural records were carried out and two competing objectives were examined: minimisation of the deflection of the isolation layer and minimisation of the total drift of the superstructure.The results show not only the effectiveness of optimal FVDs but also the fact that their optimal linearity degree depends to a great extent on the non-linear seismic response of the structure, i.e., on the type of earthquake. The simplest design approach, consisting of applying an optimization algorithm for each design accelerogram, did not seem, in this case, to be sufficient to identify the best overall design solution. The design consequences of these findings are discussed.

Analytical layerwise stress and deformation analysis of laminated composite plates with arbitrary shapes of interfacial imperfections and discontinuous lateral deflections

In the present article, a double power series analytical layerwise model is proposed for analysis of multilayer orthotropic plates with arbitrary shapes of interfacial bond defects. In contrast to the previous models, the discontinuity in the lateral deflections of the successive layers is also considered. The adhesive bonding layers are modeled by elastic elements with normal and shear stiffness coefficients; so that, the continuity conditions of the transverse shear and normal stresses are met at the layer interfaces. It is the first time that an analytical solution rather than the data-dependent finite element method is proposed for stress and displacement analysis of multilayer rectangular plates with arbitrary shapes of interfacial bond damages, including the discontinuity in the transverse displacements of the successive layers. Results of the transverse displacement and stresses are then refined according to the 3D theory of elasticity. Results reveal that even small violations in the bonding between layers, may increase the resulting stresses, lateral deflections, and the differences between lateral deflections of the successive layers to more than twice, thrice, and five times, respectively. Moreover, in contrast to the growth of the in-plane stresses, redistribution of the transverse shear stress is governed by the equilibrium rather than the constitutive-law-based conditions.

Temperature-dependent layer breathing modes in two-dimensional materials

Relative out-of-plane displacements of the constituent layers of two-dimensional materials give rise to unique low-frequency breathing modes. By computing the height-height correlation functions from molecular dynamics simulations, we show that the layer breathing modes (LBMs) can be mapped consistently to vibrations of a simple linear chain model. Our calculated thickness dependence of LBM frequencies for few-layer (FL) graphene and molybdenum disulfide $({\mathrm{MoS}}_{2})$ are in excellent agreement with available experiments. Our results show a redshift of LBM frequency with an increase in temperature, which is a direct consequence of anharmonicities present in the interlayer interaction. We also predict the thickness and temperature dependence of LBM frequencies for FL hexagonal boron nitride. Our Rapid Communication provides a simple and efficient way to probe the interlayer interaction for layered materials and their heterostructures with the inclusion of anharmonic effects.

Platelet precipitate in an age-hardening Mg-Zn-Gd alloy

The structure of a unique platelet precipitate with a three close-packed layer thickness, which occurred in a Mg-1at.%Zn-2at.%Gd alloy aged at low temperatures (<∼500 K), has been determined based on scanning transmission electron microscopy and first principles calculations. The platelet precipitate is constructed by well-defined Gd networks that cause significant atomic displacements in the adjacent close-packed layer, in which the atomic sites are preferentially occupied by Zn atoms. Local Zn concentrations at the reconstructed-layer have been successfully tuned according to a similar manner of Vegard's law by reference to the local Gd-Gd interatomic distance along the c-axis. Therefore, the present platelet precipitate is found to be not a simple ordered hexagonal-close-packed Mg-Gd as previously reported, but a reconstructed ternary Mg-Zn-Gd structure.

Modeling of normal contact of elastic bodies with surface relief taken into account

An approach to account the surface relief in normal contact problems for rough bodies on the basis of an additional displacement function for asperities is considered. The method and analytic expressions for calculating the additional displacement function for one-scale and two-scale wavy relief are presented. The influence of the microrelief geometric parameters, including the number of scales and asperities density, on additional displacements of the rough layer is analyzed.

Rotor boundary layer development with inlet guide vane (IGV) wake impingement

This paper examines the transition process in a boundary layer on a rotor blade under the impingement of an inlet guide vane wake. The effects of wake strengths and the reduced frequency on the unsteady boundary layer development on a low-speed axial compressor were investigated using particle image velocimetry. The measurements were carried out at two reduced frequencies (fr = fIGVS0/U2i, fr = 1.35, and fr = 0.675) with the Reynolds number, based on the blade chord and the isentropic inlet velocity, being 97 500. At fr = 1.35, the flow separated at the trailing edge when the wake strength was weak. However, the separation was almost totally suppressed as the wake strength increased. For the stronger wake, both the wake’s high turbulence and the negative jet behavior of the wake dominated the interaction between the unsteady wake and the separated boundary layer on the suction surface of the airfoil. The boundary layer displacement thickened first due to the negative jet effect. Then, as the disturbances developed underneath the wake, the boundary layer thickness reduced gradually. The high disturbance region convected downstream at a fraction of the free-stream velocity and spread in the streamwise direction. The separation on the suction surface was suppressed until the next wake’s arrival. Because of the long recovery time at fr = 0.675, the boundary layer thickened gradually as the wake convected further downstream and finally separated due to the adverse pressure gradient. The different boundary layer states in turn affected the development of disturbances.

The primate fovea: Structure, function and development.

A fovea is a pitted invagination in the inner retinal tissue (fovea interna) that overlies an area of photoreceptors specialized for high acuity vision (fovea externa). Although the shape of the vertebrate fovea varies considerably among the species, there are two basic types. The retina of many predatory fish, reptilians, and birds possess one (or two) convexiclivate fovea(s), while the retina of higher primates contains a concaviclivate fovea. By refraction of the incoming light, the convexiclivate fovea may function as image enlarger, focus indicator, and movement detector. By centrifugal displacement of the inner retinal layers, which increases the transparency of the central foveal tissue (the foveola), the primate fovea interna improves the quality of the image received by the central photoreceptors. In this review, we summarize ‒ with the focus on Müller cells of the human and macaque fovea ‒ data regarding the structure of the primate fovea, discuss various aspects of the optical function of the fovea, and propose a model of foveal development. The "Müller cell cone" of the foveola comprises specialized Müller cells which do not support neuronal activity but may serve optical and structural functions. In addition to the "Müller cell cone", structural stabilization of the foveal morphology may be provided by the 'z-shaped' Müller cells of the fovea walls, via exerting tractional forces onto Henle fibers. The spatial distribution of glial fibrillary acidic protein may suggest that the foveola and the Henle fiber layer are subjects to mechanical stress. During development, the foveal pit is proposed to be formed by a vertical contraction of the centralmost Müller cells. After widening of the foveal pit likely mediated by retracting astrocytes, Henle fibers are formed by horizontal contraction of Müller cell processes in the outer plexiform layer and the centripetal displacement of photoreceptors. A better understanding of the molecular, cellular, and mechanical factors involved in the developmental morphogenesis and the structural stabilization of the fovea may help to explain the (patho-) genesis of foveal hypoplasia and macular holes.

A closed-form analytical model for predicting 3D boundary layer displacement thickness for the validation of viscous flow solvers

A closed-form analytical model is developed for estimating the 3D boundary-layer-displacement thickness of an internal flow system at the Sanal flow choking condition for adiabatic flows obeying the physics of compressible viscous fluids. At this unique condition the boundary-layer blockage induced fluid-throat choking and the adiabatic wall-friction persuaded flow choking occur at a single sonic-fluid-throat location. The beauty and novelty of this model is that without missing the flow physics we could predict the exact boundary-layer blockage of both 2D and 3D cases at the sonic-fluid-throat from the known values of the inlet Mach number, the adiabatic index of the gas and the inlet port diameter of the internal flow system. We found that the 3D blockage factor is 47.33 % lower than the 2D blockage factor with air as the working fluid. We concluded that the exact prediction of the boundary-layer-displacement thickness at the sonic-fluid-throat provides a means to correctly pinpoint the causes of errors of the viscous flow solvers. The methodology presented herein with state-of-the-art will play pivotal roles in future physical and biological sciences for a credible verification, calibration and validation of various viscous flow solvers for high-fidelity 2D/3D numerical simulations of real-world flows. Furthermore, our closed-form analytical model will be useful for the solid and hybrid rocket designers for the grain-port-geometry optimization of new generation single-stage-to-orbit dual-thrust-motors with the highest promising propellant loading density within the given envelope without manifestation of the Sanal flow choking leading to possible shock waves causing catastrophic failures.

Modification of hypersonic waveriders by vorticity-based boundary layer displacement thickness determination method

For general hypersonic vehicles flying at high altitudes and Mach numbers, the appearance of the large boundary layer displacement thickness can change the pressure distribution and aerodynamic characteristics significantly. As for the waverider, another side effect is that the shock wave position is deflected downward evidently even at the design Mach number, which is adverse for the shock wave being attached to the leading edge and may lead to more leakage of high pressure gas from the lower surface onto the upper surface. Therefore, this paper first develops a vorticity-based method to determine the boundary layer displacement thickness, in combination with the tangent wedge/cone method. Then, trying to alleviate the high pressure gas leakage near the leading edge, modification of a viscous optimized waverider is conducted under the condition of strong viscous interaction, by deducting the corresponding boundary layer displacement thickness from the original lower surface along the normal direction. Results show that the shock wave position around the lower surface of the modified waverider under the condition of strong viscous interaction is very close to that of the inviscid basic flowfield around the original waverider, which means less leakage of high pressure gas. But it's found that such change has little influence on the aerodynamic characteristics of the upper surface. However, an interesting discovery is that due to the lower pressure near the leading edge of the modified lower surface, the wave drag is lowered for the same lift, thus the lift-to-drag ratio is improved. The modified waverider also exhibits higher lift-to-drag ratio at large angles of attack when compared to waveriders with upper expansion surfaces. Overall, a vorticity-based boundary layer displacement thickness determination method is proposed in this paper, which is then used to modify waveriders to achieve higher aerodynamic efficiency.

Surface Localization in Impurity Band with Random Displacements and Long-Range Interactions

We study the random Schrödinger operators in a Euclidean space with the disorder generated by two complementary mechanisms: random substitution in a lower-dimensional layer and random displacements in the bulk, without additional assumptions regarding the reflection symmetry of the site potentials. The latter are assumed to be bounded and have a power-law decay. Complementing earlier results obtained in the strong disorder regime, we establish spectral and strong dynamical localization in the impurity zone near the bottom of spectrum for arbitrarily weak amplitudes of the random displacements, provided the concentration of impurities is sufficiently small.

METHOD OF SOLVING THE INVERSE PROBLEM FOR WING–FUSELAGE COMBINATION USING REYNOLDS-AVERAGED NAVIER–STOKES EQUATIONS

In this study, an iteration method has been developed for construction of the wing geometry using a prescribed pressure distribution for a wing–fuselage combination in the compressible flow of a viscous gas within the framework of the Reynolds-averaged Navier–Stokes equations. The method belongs to the class of residual corrections methods. The wing surface deformation reducing the residual correction between the computed and objective pressure distribution is determined by solving the inverse problem for the same combination in the potential flow of a compressible gas by taking into account the effect of the boundary layer displacement thickness and the wake behind the wing. Examples of the wing geometry construction using the prescribed pressure distribution and demonstrating the high rate of method convergence (3–4 iterations) are presented.