Three-dimensional Situation Research Articles

Analysis of three-dimensional transient seepage into ditch drains from a ponded field

An analytical solution in the form of infinite series is developed for predicting time-dependent three-dimensional seepage into ditch drains from a flat, homogeneous and anisotropic ponded field of finite size, the field being assumed to be surrounded on all its vertical faces by ditch drains with unequal water level heights in them. It is also assumed that the field is being underlain by a horizontal impervious barrier at a finite distance from the surface of the soil and that all the ditches are being dug all the way up to this barrier. The solution can account for a variable ponding distribution at the surface of the field. The correctness of the proposed solution for a few simplified situations is tested by comparing predictions obtained from it with the corresponding values attained from the analytical and experimental works of others. Further, a numerical check on it is also performed using the Processing MODFLOW environment. It is noticed that considerable improvement on the uniformity of the distribution of the flow lines in a three-dimensional ponded drainage space can be achieved by suitably altering the ponding distribution at the surface of the soil. As the developed three-dimensional ditch drainage model is pretty general in nature and includes most of the common variables of a ditch drainage system, it is hoped that the drainage designs based on it for reclaiming salt-affected and water-logged soils would prove to be more efficient and cost-effective as compared with designs based on solutions developed by making use of more restrictive assumptions. Also, as the developed model can handle three-dimensional flow situations, it is expected to provide reliable and realistic drainage solutions to real field situations than models being developed utilizing the two-dimensional flow assumption. This is because the existing two-dimensional solutions to the problem are actually valid not for a field of finite size but for an infinite one only.

An approach to consider lateral heat conduction effects in the evaluation process of transient heat transfer measurements using TLC

The standard transient evaluation technique for the experimental determination of heat transfer coefficients with Thermochromic Liquid Crystals is based on a one-dimensional heat conduction model inside a semi-infinite wall. However, complex flow situations induced by obstacles like cylinders, skewed ribs or vortex generators lead to spatially varying heat transfer coefficients and therefore to lateral conduction effects. Kingsley-Rowe et al. [1] developed an analytical empirical correction method considering these effects for flat two-dimensional heat conduction problems and an ideal step change of the fluid reference temperature. This method is expanded to capture three-dimensional heat conduction situations and slow transient fluid reference temperature changes. Transient simulations for twelve different heat transfer coefficient distributions and three different reference temperature histories constitute the pool of data for the determination of the empirical constants and the validation of the method. The results showed an appropriate correction of the heat transfer coefficients received by the standard evaluation method. Therefore the presented method offers the opportunity to consider three-dimensional heat conduction effects in a fast and efficient way in combination with the standard evaluation process.

Single molecules as whispering galleries for electrons

Whispering gallery modes, well-known for acoustic and optical waves, have been shown recently for electrons in molecules on surfaces. The existence of such waves opens new possibilities for nanoelectronic devices. Here we propose a simple analytical textbook model which allows the main characteristic features of such electronic waves to be understood. The model is illustrated by two- and three-dimensional experimental situations.

Good Posture, Good Balance: Comparison of Bioinspired and Model-Based Approaches for Posture Control of Humanoid Robots

This article provides a theoretical and thorough experimental comparison of two distinct posture control approaches: 1) a fully model-based control approach and 2) a biologically inspired approach derived from human observations. While the robotic approach can easily be applied to balancing in three-dimensional (3-D) and multicontact (MC) situations, the biologically inspired balancer currently only works in two-dimensional situations but shows interesting robustness properties under time delays in the feedback loop. This is an important feature when considering the signal transmission and processing properties in the human sensorimotor system. Both controllers were evaluated in a series of experiments with a torque-controlled humanoid robot (TORO). This article concludes with some suggestions for the improvement of model-based balancing approaches in robotics.

Simulation of Individual Polymer Chains and Polymer Solutions with Smoothed Dissipative Particle Dynamics

In an earlier work (Litvinov et al., Phys.Rev.E 77, 066703 (2008)), a model for a polymer molecule in solution based on the smoothed dissipative particle dynamics method (SDPD) has been presented. In the present paper, we show that the model can be extended to three-dimensional situations and simulate effectively diluted and concentrated polymer solutions. For an isolated suspended polymer, calculated static and dynamic properties agree well with previous numerical studies and theoretical predictions based on the Zimm model. This implies that hydrodynamic interactions are fully developed and correctly reproduced under the current simulated conditions. Simulations of polymer solutions and melts are also performed using a reverse Poiseuille flow setup. The resulting steady rheological properties (viscosity, normal stress coefficients) are extracted from the simulations and the results are compared with the previous numerical studies, showing good results.

Thermodynamics of Yukawa fluids near the one-component-plasma limit

Thermodynamics of weakly screened (near the one-component-plasma limit) Yukawa fluids in two and three dimensions is analyzed in detail. It is shown that the thermal component of the excess internal energy of these fluids, when expressed in terms of the properly normalized coupling strength, exhibits the scaling pertinent to the corresponding one-component-plasma limit (the scalings differ considerably between the two- and three-dimensional situations). This provides us with a simple and accurate practical tool to estimate thermodynamic properties of weakly screened Yukawa fluids. Particular attention is paid to the two-dimensional fluids, for which several important thermodynamic quantities are calculated to illustrate the application of the approach.

Differentiation of Wharton's Jelly-Derived Mesenchymal Stem Cells into Motor Neuron-Like Cells on Three-Dimensional Collagen-Grafted Nanofibers.

Cell transplantation strategies have provided potential therapeutic approaches for treatment of neurodegenerative diseases. Mesenchymal stem cells from Wharton's jelly (WJMSCs) are abundant and available adult stem cells with low immunological incompatibility, which could be considered for cell replacement therapy in the future. However, MSC transplantation without any induction or support material causes poor control of cell viability and differentiation. In this study, we investigated the effect of the nanoscaffolds on WJMSCs differentiation into motor neuronal lineages in the presence of retinoic acid (RA) and sonic hedgehog (Shh). Surface properties of scaffolds have been shown to significantly influence cell behaviors such as adhesion, proliferation, and differentiation. Therefore, polycaprolactone (PCL) nanofibers were constructed via electrospinning, surface modified by plasma treatment, and grafted by collagen. Characterization of the scaffolds by means of ATR-FTIR, contact angel, and Bradford proved grafting of the collagen on the surface of the scaffolds. WJMSCs were seeded on nanofibrous and tissue culture plate (TCP) and viability of WJMSCs were measured by MTT assay and then induced to differentiate into motor neuron-like cells for 15 days. Differentiated cells were evaluated morphologically, and real-time PCR and immunocytochemistry methods were done to evaluate expression of motor neuron-like cell markers in mRNA and protein levels. Our results showed that obtained cells could express motor neuron biomarkers at both RNA and protein levels, but the survival and differentiation of WJMSCs into motor neuron-like cells on the PCL/collagen scaffold were higher than cultured cells in the TCP and PCL groups. Taken together, WJMSCs are an attractive stem cell source for inducing into motor neurons in vitro especially when grown on nanostructural scaffolds and PCL/collagen scaffolds can provide a suitable, three-dimensional situation for neuronal survival and differentiation that suggest their potential application towards nerve regeneration.

Folded Compositions in Architecture: Spatial Properties and Materials

The two-dimensional unfolding of three-dimensional volumes allows architectural design and production methods to be rethought in a creative way. This paper reviews spatial and material properties of folded compositions in architecture, through a conceptual proposal based on professional and pedagogic experiences as well as new technologies for geometrical programming and digital fabrication, tested in five alternatives for one case study. The continuous and dynamic two-dimensional projection of a three-dimensional spatial situation provides a geometric relationship between the surface and volumetric configuration of a design, thus enabling a mathematical and operative connection between conditions of perception and production. The material expression of these configurations establishes a significant link between the conceptualisation of the design form, its geometric digital generation, its physical fabrication and overall appearance in a manner analogous to the design process used. The combination of folded compositions with the new technologies available further strengthens their potential, which embraces the fluid nature of human activity with continuous forms and delicately intricate geometries.

Experimental study of transport of a dimer on a vertically oscillating plate.

It has recently been shown that a dimer, composed of two identical spheres rigidly connected by a rod, under harmonic vertical vibration can exhibit a self-ordered transport behaviour. In this case, the mass centre of the dimer will perform a circular orbit in the horizontal plane, or a straight line if confined between parallel walls. In order to validate the numerical discoveries, we experimentally investigate the temporal evolution of the dimer's motion in both two- and three-dimensional situations. A stereoscopic vision method with a pair of high-speed cameras is adopted to perform omnidirectional measurements. All the cases studied in our experiments are also simulated using an existing numerical model. The combined investigations detail the dimer's dynamics and clearly show that its transport behaviours originate from a series of combinations of different contact states. This series is critical to our understanding of the transport properties in the dimer's motion and related self-ordered phenomena in granular systems.

Evaluation of Motor Neuron-Like Cell Differentiation of hEnSCs on Biodegradable PLGA Nanofiber Scaffolds.

Human endometrium is a high-dynamic tissue that contains human endometrial stem cells (hEnSCs) which can be differentiated into a number of cell lineages. The differentiation of hEnSCs into many cell lineages such as osteoblast, adipocyte, and neural cells has been investigated previously. However, the differentiation of these stem cells into motor neuron-like cells has not been investigated yet. Different biochemical and topographical cues can affect the differentiation of stem cells into a specific cell. The aim of this study was to investigate the capability of hEnSCs to be differentiated into motor neuron-like cells under biochemical and topographical cues. The biocompatible and biodegradable poly(lactic-co-glycolic acid) (PLGA) electrospun nanofibrous scaffold was used as a topographical cue. Human EnSCs were cultured on the PLGA scaffold and tissue culture polystyrene (TCP), then differentiation of hEnSCs into motor neuron-like cells under induction media including retinoic acid (RA) and sonic hedgehog (Shh) were evaluated for 15 days. The proliferation rate of cells was assayed by using MTT assay. The morphology of cells was studied by scanning electron microscopy imaging, and the expression of motor neuron-specific markers by real-time PCR and immunocytochemistry. Results showed that survival and differentiation of hEnSCs into motor neuron-like cells on the PLGA scaffold were better than those on the TCP group. Taken together, the results suggest that differentiated hEnSCs on PLGA can provide a suitable, three-dimensional situation for neuronal survival and outgrowth for regeneration of the central nervous system, and these cells may be a potential candidate in cellular therapy for motor neuron diseases.

Theoretical Study of Size Effects on Surface Chemical Properties for Nanoscale Diamond Particles

Nanodiamond has displayed some unique physical and chemical properties compared to bulk diamond, which broadens its applications in various areas. However, a more detailed picture of nanodiamond quantum confinements is still missing from a theoretical point of view. This investigation presents a study where the effects of one-dimension (i.e., diamond thin films) and three-dimension (i.e., nanodiamond particles) confinement on surface reactivity, and properties, have been calculated using density functional theory (DFT) and tight binding density functional theory (DFTB) methods. Surface specific parameters like (i) surface C–H bond length, (ii) atomic charges, (iii) H adsorption energy, (iv) highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), (v) band gap, and (vi) Fukui functions were thereby carefully calculated and compared. For both the one-dimensional diamond thin films of different surface planes, quantum confinements have strong influences on these factors from thickness of 0.2 to ∼1 nm, while for thin films thicker than 1 nm, the values stabilize around a plateau value. For three-dimensional situations, these factors were found to change within a range of nanodiamond diameter of 0.4 to ∼2 nm, followed by oscillations around specific values as well. These results reveal that nanoscale diamond quantum confinements exist for a nanodiamond particle of a diameter smaller than 2 nm, but not for larger particle sizes. It must here be stressed that all surface specific parameters did independently show the existence of the here presented size ranges for quantum confinement.

A hybridizable discontinuous Galerkin formulation for non-linear elasticity

We revisit the hybridizable discontinuous Galerkin method for non-linear elasticity introduced by S.-C. Soon (2008). We show that it can be recast as a minimization problem of a non-linear functional over a space of discontinuous approximations to the displacement. The functional can be written as the sum over the elements of the classic potential energy plus a new energy associated to the inter-element jumps of the displacement. We then show that if this new energy is not properly weighted, the minimizers might not converge to the exact solution. We construct an example illustrating this phenomenon and show how to overcome it by suitably increasing the weight of the energy of the inter-element jumps. Finally, we explore the performance of the method for the case of piecewise-linear approximations in rather demanding situations in both two-dimensional and, for the first time, three-dimensional situations. They include almost incompressible materials, large deformations with large-shear layers, and cavitation. We also compare the method with the continuous Galerkin method and a previously explored discontinuous Galerkin method, and show that, when using piecewise-linear approximations and a moderate number of degrees of freedom, the current method turns out to be more efficient for the computation of the gradient.

Destruction of superconductivity in disordered materials: A dimensional crossover

The disorder-induced superconductor-to-insulator transition in amorphous ${\mathrm{Nb}}_{x}{\mathrm{Si}}_{1\ensuremath{-}x}$ two-dimensional thin films is studied for different niobium compositions $x$ through a variation of the sample thickness $d$. We show that the critical thickness ${d}_{c}$, separating a superconducting regime from an insulating one, increases strongly with diminishing $x$, thus attaining values of over 100 \AA{}. The corresponding phase diagram in the $(d,x)$ plane is inferred and related to the three-dimensional situation. The two-dimensional superconductor-to-insulator transition well connects with the three-dimensional superconductor-to-metal transition.

Precursors for waves in random media

We consider scattering of a pulse propagating through a three-dimensional random media and study the shape of the pulse in the parabolic approximation. We show that, similarly to the one-dimensional O’Doherty–Anstey theory, the pulse undergoes a deterministic broadening. Its amplitude decays only algebraically and not exponentially in time, due to the signal low/midrange frequency component. We also argue that the parabolic approximation captures the front evolution (but not the signal away from the front) correctly even in the fully three-dimensional situation.

A simplified model to analyze the reinforced piled embankments

It is an economic way to use the piled embankment for the construction of embankment over soft soil. The combination of piles and reinforcement can effectively reduce the differential settlement at the surface of embankment. The paper presents a simplified model for analysis of an embankment of granular fill on soft ground supported by reinforcement and piles. This model is based on consideration of the arching effect in granular material proposed by Hewlett & Randolph. The vertical equilibrium of the unit body at the center of pile caps immediately below the reinforcement is established. The refinements of the model are that the failure mechanisms of the arch both at the crown and at the pile cap were considered, three-dimensional situation was taken into account for reinforced piled embankment, calculation of the vertical stress carried by the subsoil due to arching effect and reinforcement for multi-layered soil was proposed. Using the simplified model, the influence of embankment height, one-dimensional compression modulus of subsoil, tensile stiffness of reinforcement on stress reduction ratio (SRR) and tensile force of reinforcement is investigated. It is found that the model can be used to assess the relative contribution of the reinforcement and subsoil. The results show that subsoil gives a major contribution to overall vertical equilibrium, while the reinforcement gives obvious contribution at relatively large settlement. The inclusion of the reinforcement can reduce the vertical stress acting on the subsoil. The simplified model is then evaluated by three case studies. The results of this model show good consistence with these cases.

Harvesting light with transformation optics

Transformation optics (TO) is a new tool for controlling electromagnetic fields. In the context of metamaterial technology, it provides a direct link between a desired electromagnetic (EM) phenomenon and the material response required for its occurrence. Recently, this powerful framework has been successfully exploited to study surface plasmon assisted phenomena such as light harvesting. Here, we review the general strategy based on TO to design plasmonic devices capable of harvesting light over a broadband spectrum and achieving considerable field confinement and enhancement. The methodology starts with two-dimensional (2D) cases, such as 2D metal edges, crescent-shaped cylinders, nanowire dimers, and rough metal surfaces, and has been well extended to fully-fledged three-dimensional (3D) situations. The largely analytic approach gives physical insights into the processes involved and suggests the way forward to study a wide variety of plasmonic nanostructures.

On the Simultaneous Motions of Many Blood Cells

Readers who have mentally juggled to compare models of thrombosis based on discrete concepts with those based on continuum representations will enjoy the article by Skorczewski et al. (1) because they bring first-principles methods to provide a fascinating description of the motions of red blood cells, platelets, and events in flows over a prototypical thrombotic mound. The temporal dynamics of the situation are captured over many scales in an exemplary two-dimensional situation as the red cells control most of the available space, block direct motions to the wall, and are less likely to be present near the wall. The size of the near-wall region is visibly changed when the hematocrit of the flow changes. And, the platelet dynamics, their individual behaviors in the flow field, is shown to differ for lower and higher hematocrits. The authors’ work sets a standard for careful depiction of the flow-driven events involving interactions among red cells and platelets, for computing local descriptions of platelet exposure, and for representing the totality of events for distinct values of the average hematocrit. Readers can be assured that proper methods were implemented for the computations used to uncover the applicable shear strain rates and shear (or other) stress distributions at all sites in the flow and that these events induced the gradients of concentration and effective diffusion coefficient. The movies that are a part of the article’s Supporting Material will help the reader appreciate the dynamism that is connected with exposure to biochemical agents and processes. As you enjoy the article, think of the steps that will come with increased computational power. This framework is sturdy enough for work in three dimensions and for including more of the applicable biochemistry and cellular biology. Recognizing the physiological and pathological importance of thrombotic events in flowing blood, many readers and contributors to Biophysical Journal work in or follow the field. Our New & Notable paper joins a group (2–5) that has addressed the larger multiscale problem. Each of them followed the precepts of the Biophysical Society, and the Biophysical Journal, by making effective use of mathematical depictions, models, and experimental data. These four works illustrate major aspects of thrombosis and hemostasis that are within our readers’ purviews; however, the list is too short to capture all the important contributions by the Biophysical Journal community on this general topic. Direct treatment of the total three-dimensional situation, with its nonlinearity and many elements, is still our dream. Yet strong attacks on specific aspects are possible when numerical means are combined with sound data. This is true especially when the numerical studies are based in sound mathematical science, the results are verified by their ability to capture the prior experimental findings, and the studies predict behaviors that can be sought in future experiments. Most importantly, the numerical means will permit workers to explore details that are extremely difficult or even impossible to capture experimentally, and thereby extend our understanding of the intrinsic processes.

On topologically massive spin-2 gauge theories beyond three dimensions

We investigate in which sense, at the linearized level, one can extend the 3D topologically massive gravity theory beyond three dimensions. We show that, for each k=1,2,3,⋯ afreetopologicallymassivegaugetheoryin4k−1dimensionscanbedefined describing a massive “spin-2” particle provided one uses a non-standard representation of the massive “spin-2” state which makes use of a two-column Young tableau where each column is of height 2k − 1. We work out the case of k = 2, i.e. 7D, and show, by canonical analysis, that the model describes, unitarily, 35 massive “spin-2” degrees of freedom. The issue of interactions is discussed and compared with the three-dimensional situation.

Laser nitriding of the surface of phosphor bronze

Phosphorous bronze finds applications in industry because of its resistance to fatigue and ease of heat dissipation due to its high thermal conductivity. Laser treatment of bronze surface improves the hardness of the surface through forming a dense layer in the surface region. Consequently, in the present study, laser treatment of a bronze surface is investigated. Thermal stress and temperature fields developed during the laser-treated region are modeled after considering the transient three-dimensional situation in line with the experimental conditions. An experiment is carried out, and the resulting surfaces treated by a laser beam are characterized using scanning electron microscope, energy dispersive spectroscopy, and X-ray diffraction. It is found that high rate of strain developed in the heated region, due to fast-cooling rates, results in high von Mises stress in the surface region. The laser-treated region is free from cracks, and surface hardness increases almost four times above the base material hardness after the laser treatment process.

Cutter force measurement on tunnel boring machines – System design

Loading of a TBM disc cutter is usually derived by dividing the total thrust by the number of cutters which gives an approximate average loading of 250kN for a typical 17″ cutter. However, laboratory cutting tests infer that the loading of a cutter oscillates strongly and can reach peaks that are a multiple of the average forces. Knowledge of the true forces acting on a disc cutter is of great importance to gain further insight in areas such as cutter wear, brittle fracture of cutter rings, fatigue and the mechanism of rock breakage in different geological formations.Consequently, the development of a measurement method to determine the three-dimensional loading situation of a disc cutter in real-time was conducted. An investigation of the deformation state of a typical disc cutter and its casing was performed by means of the finite element method. Subsequently, a measurement method that isn’t affected by cutter change was developed by finding suitable spots for sensor placement in the cutter saddle. Laboratory tests proved the feasibility of the developed measurement method that is now ready for implementation on a TBM.