Two-dimensional Objects Research Articles

Treating grain growth in thin films in three dimensions: A simulation study

Historically, metallography has been the two-dimensional characterization of materials microstructures by optical microscopy. Consequential problems have long been known: A two-dimensional section through a three-dimensional object gives us only a very poor idea about size and form of the object. Therefore, many attempts have been made to gain three-dimensional information experimentally. Nevertheless, in simulations and also analytical theories thin films are commonly still treated as two-dimensional objects making comparisons with 3D experimental data rather hard. In the present paper, grain growth in thin films is investigated for the first time by three-dimensional Potts model simulations focusing particularly on the transition from bulk-like growth to columnar microstructures.

Two-Dimensional Object Detection Using Accumulated Cell Average Constant False Alarm Rate

The extensive work in SONAR is oceanic Engineering which is one of the most developing researches in engineering. The SideScan Sonars (SSS) are one of the most utilized devices to obtain acoustic images of the seafloor. This paper proposes an approach for developing an efficient system for automatic object detection utilizing the technique of accumulated cell average-constant false alarm rate in 2D (ACA-CFAR2D), where the optimization of the computational effort is achieved. This approach employs image segmentation as preprocessing step for object detection, which have provided similar results with other approaches like undecimated discrete wavelet transform (UDWT), watershed and active contour techniques. The SSS sea bottom images are segmented for the 2D object detection using these four techniques and the segmented images are compared along with the experimental results of the proportion of segmented image (P) and runtime in seconds (T) are presented.

Rancang Bangun Aplikasi Augmented Reality Museum Bali Berbasis Android Studi Kasus Gedung Karangasem dan Gedung Tabanan

Museum Bali is one of the museum which is located in Denpasar City that established since 1910. The Museum collections consist of items such as living equipment, art, religion, handwriting, and other things that show the situation and the development of the Balinese culture. Augmented Reality is a technology which combines two-dimensional virtual objects or three-dimensional virtual objects into the real environment. Museum Bali has decreased the amount of visitors in recent years and requires an innovation to promote Museum Bali. One innovation that is expected to promote the Museum Bali is to create an augmented reality application that called Augmented Reality Museum Bali in Android platform. Utilizing augmented reality technology that works by detecting the marker then it show up the 3D object and the information from one of the objectsin Museum Bali. Markerless method used in detection marker that make this application moreattractive and expected to be a new experience for the people who want to know more about Museum Bali.

Two-Dimensional Colloidal Nanocrystals.

In this paper, we review recent progress on colloidal growth of 2D nanocrystals. We identify the four main sources of anisotropy which lead to the formation of plate- and sheet-like colloidal nanomaterials. Defect-induced anisotropy is a growth method which relies on the presence of topological defects at the nanoscale to induce 2D shapes objects. Such a method is particularly important in the growth of metallic nano-objects. Another way to induce anisotropy is based on ligand engineering. The availability of some nanocrystal facets can be tuned by selectively covering the surface with ligands of tunable thickness. Cadmium chalcogenides nanoplatelets (NPLs) strongly rely on this method which offers atomic control in the thinner direction, down to a few monolayers. Two-dimensional objects can also be obtained by post or in situ self-assembly of nanocrystals. This growth method differs from the previous ones in the sense that the elementary objects are not molecular precursors and is a common method for lead chalcogenide compounds. Finally, anisotropy may simply rely on the lattice anisotropy itself as it is common for rod-like nanocrystals. Colloidally grown transition metal dichalcogenides (TMDC) in particular result from such process. We also present hybrid syntheses which combine several of the previously described methods and other paths, such as cation exchange, which expand the range of available materials. Finally, we discuss in which sense 2D objects differ from 0D nanocrystals and review some of their applications in optoelectronics, including lasing and photodetection, and biology.

Microwave Imaging under Oblique Illumination.

Microwave imaging based on inverse scattering problem has been attracting many interests in the microwave society. Among some major technical challenges, the ill-posed, multi-dimensional inversion algorithm and the complicated measurement setup are critical ones that prevent it from practical applications. In this paper, we experimentally investigate the performance of the subspace-based optimization method (SOM) for two-dimensional objects when it was applied to a setup designed for oblique incidence. Analytical, simulation, and experimental results show that, for 2D objects, neglecting the cross-polarization scattering will not cause a notable loss of information. Our method can be potentially used in practical imaging applications for 2D-like objects, such as human limbs.

Dynamic colloidal assembly pathways via low dimensional models.

Here we construct a low-dimensional Smoluchowski model for electric field mediated colloidal crystallization using Brownian dynamic simulations, which were previously matched to experiments. Diffusion mapping is used to infer dimensionality and confirm the use of two order parameters, one for degree of condensation and one for global crystallinity. Free energy and diffusivity landscapes are obtained as the coefficients of a low-dimensional Smoluchowski equation to capture the thermodynamics and kinetics of microstructure evolution. The resulting low-dimensional model quantitatively captures the dynamics of different assembly pathways between fluid, polycrystal, and single crystals states, in agreement with the full N-dimensional data as characterized by first passage time distributions. Numerical solution of the low-dimensional Smoluchowski equation reveals statistical properties of the dynamic evolution of states vs. applied field amplitude and system size. The low-dimensional Smoluchowski equation and associated landscapes calculated here can serve as models for predictive control of electric field mediated assembly of colloidal ensembles into two-dimensional crystalline objects.

Massless surface waves between two different superfluid phases ofHe3

An interface between two media is topologically stable two-dimensional object where 3D-symmetry breaks which allows for existence of many exotic excitations. A direct way to explore surface excitations is to investigate their interaction with the surface waves, such as very well known capillary-gravity waves and crystallization waves. Helium remains liquid down to absolute zero where bulk excitations are frozen out and do not mask the interaction of the waves with the surface states. Here we show the possibility of the new, massless wave which can propagate along the surface between two different superfluids phases of $^3$He. The displacement of the surface in this wave occurs due to the transition of helium atoms from one phase to another, so that there is no flow of particles as densities of phases are equal. We calculate the dispersion of the wave in which the inertia is provided by spin supercurrents, and the restoring force is magnetic field gradient. We calculate the dissipation of the wave and show the preferable conditions to observe it.

Janus Nanofilms.

To make a two-dimensional Janus object, the perfluorinated anionic polyelectrolyte Nafion was adsorbed to the surface of ultrathin films of polyelectrolyte complex. Nafion changed the wetting characteristics of the polyelectrolyte multilayer (PEMU) of poly(diallyldimethylammonium) and poly(styrenesulfonate) from hydrophilic to hydrophobic. PEMUs assembled on aluminum substrates and terminated with Nafion could be released by exposure to alkali solution, producing free-floating films in the 100 nm thickness regime. Water contact angle measurements showed a strong difference in hydrophilicity between the two sides of this Janus film, which was further characterized using atomic force microscopy and X-ray photoelectron spectroscopy (XPS). XPS revealed different fluorine contents on both sides of the PEMU, which could be translated to a Nafion gradient through the film. Fourier transform infrared spectroscopy showed the Nafion-containing films were much more resistant to decomposition by high salt concentration.

Visual defects when extending two-dimensional invisible lenses with circular symmetry into the third-dimension

A common practice in the design of three-dimensional objects with transformation optics is to first design a two-dimensional object and then to simply extend the refractive index profile along the z-axis. For lenses that are transformations of free space, this technique works perfectly, but for many lenses that seem like they would work, this technique causes optical distortions. In this paper, we analyze two such cases, the invisible sphere and Eaton lens, and show photorealistically how serious such optical distortions might appear in practice.

Elliptic Filter and Iterative Inversion Method for Buried Object Detection Applications

In this paper, Forward-Backward Time-Stepping (FBTS) inversion method is used for detection, imaging and reconstruction of an unknown object in a region of interest. We consider the reconstruction parameter profiles of two-dimensional objects from measurement of the transient total electromagnetic field data contaminated with noise. A preliminary result of an Elliptic filter integrated in FBTS algorithm to suppress noise effect has been obtained. A circular shape in the region of interest is successfully detected and reconstructed.

A NURBS based Galerkin approach for the analysis of solids in boundary representation

The paper is concerned with a new numerical method to solve the elasticity problem of solids in boundary representation. A formulation is derived where the geometrical description of the boundary is sufficient for defining the equations of elasticity of the complete solid. While the interior of the domain is described by a radial scaling parameter, the scaling of the boundary with respect to the specified scaling center leads to the complete solid. This idea fits perfectly to the boundary representation modeling technique commonly employed in CAD. In the present approach the tensor-product structure of the solid will be reduced by one dimension to parametrize the physical domain, i.e., the three-dimensional solid exploits only two-dimensional NURBS objects, which parametrize the boundary surfaces. For the analysis, the weak form of the equilibrium equations is enforced for the entire solid. In particular the weak form is employed in the scaling direction and the circumferential direction. Applying the isogeometric paradigm, the NURBS functions that describe the boundary of the geometry form also the basis for the approximation of the displacement at the boundary. The displacement response in the radial scaling direction, on the other hand, is approximated by a one-dimensional NURBS. Overall, the Galerkin projection of the weak form yields a linear system of equilibrium equations whose solution gives rise to the displacement response. The accuracy of the method is validated by means of analytical reference data. In conclusion, the proposed method allows the analysis of solids which are bounded by an arbitrary number of contour boundaries.

A new archive of heat transfer coefficients from square and chamfered cylinders at angles of attack in crossflow

Calculations of convection heat transfer coefficients between a fluid in crossflow and two-dimensional square-cylindrical objects have been performed using numerical simulation. Some calculations included geometries with chamfered corners while others were sharp-edged. The numerical model allows a systematic study of various angles of attack and lengths of chamfer so that the entire range of angles and chamfers were investigated. It was found that the present results are in good agreement with previously published archival values for similar geometries and Reynolds numbers. In this regard, the present work significantly expands the upper bound of the Nusselt–Reynolds correlation.Comparison among the many investigated geometrical configurations reveals that more extensive chamfering results in a lowered dependence of the Nusselt number on the Reynolds number. In the lower range of the Reynolds numbers dealt with in this study, there was near parity in the Nusselt number values for square and octagonal chamfered cylinders; however, at the higher Reynolds number range (approximately 2,000,000), the octagon Nusselt numbers were ∼80% of those of the square for a zero-degree angle of attack. The largest angle of attack (45°) also exhibited Nusselt number values that were comparable for the square and octagonal shapes in the lower range of Reynolds numbers. However, at the higher Reynolds numbers, the results differed by approximately a factor of two (square cylinder Nusselt number is larger than the octagonal Nusselt number). The results calculated here for air are extended to other fluids by a simple calculation involving the ratio of Prandtl numbers.

Rotation of millimeter-sized objects using ordinary light.

The ability to optically rotate bodies offers new degrees of control of micro-objects with applications in various domains, including microelectromechanical systems (MEMS), biomanipulations, or optofluidics. Here we demonstrate the optically-induced rotation of simple asymmetric two-dimensional objects using plane waves originating either from ordinary laser sources or from black body radiation. The objects are floating on an air/water interface. We observe a steady-state rotation depending on the light intensity and on the asymmetry of the object. We interpret this rotation in terms of light diffraction by the edges of the object. Such systems could be easily implemented in optofluidic devices to induce liquid flow without the need for special light sources.

A Study of the Method for Building up 3D Right Objects

Recently, the demand for three-dimensional spatial information has continuously been increasing, and especially, studies of indoor/outdoor spatial information or data construction have actively been conducted. However, utilization of spatial information does not universally spread to the private sector, but it is mostly used for the government offices. Thus, this study deals with the creation of three-dimensional right objects and the technique of expression to further vitalize the private sector, three-dimensional right objects, aiming to create and express three-dimensional right spaces in a particular system or open platform more conveniently. Unlike a plane text or apartment building used in existing maps was iconified and displayed simply, this study proposes a method of extracting data from the outer border of the building by the relevant level based on the existing structured three-dimensional building, a method of providing two-dimensional right spatial objects in XML, and expressing them as three-dimensional right objects efficiently. In addition, this study will discuss a method of creating right objects in a way in which an owner who was provided with a cross section of a building involves the direct detailed right objects in additional production or reproduction to utilize three-dimensional data (right objects) produced through this study.

Grasping a 2D object: terminal haptic feedback supports an absolute visuo-haptic calibration.

Grasping a three-dimensional (3D) object results in the specification of motor output via absolute size information. In contrast, the impoverished visual cues (e.g., binocular and vergence) associated with grasping a two-dimensional (2D) object are reported to render aperture formation via an object's perceptual and relative visual features. It is, however, important to recognize that 3D and 2D grasping differ not only in terms of their visual properties, but also because the latter does not entail the provision of haptic feedback. As such, the present work examined whether haptic feedback influences the nature of the information supporting 2D grasping. Participants grasped differently sized 3D objects (i.e., 3D task) and completed a 'traditional' 2D grasping task to line drawings without receiving haptic feedback (i.e., 2DH- task). As well, we included a separate condition using the same objects as the 2DH- task; however, the experimenter placed a 3D object (i.e., one corresponding to the size of the 2D object) between the thumb and forefinger of participants' grasping limb once they completed their response (i.e., 2DH+ task). Thus, the 2DH+ task provided haptic feedback related to absolute object size. Notably, we computed just-noticeable-difference (JND) scores to determine whether the different tasks adhered to, or violated, the relative psychophysical principles of Weber's law. JNDs for the 2DH- task adhered to Weber's law, whereas 3D and 2DH+ tasks violated the law. Thus, results evince that 2DH- and 2DH+ tasks are specified via relative and absolute object size information, respectively. Accordingly, we propose that haptic feedback supports an absolute visuo-haptic calibration and contend that our results highlight the importance of multi-sensory cue integration in goal-directed grasping.

Computer Technologies for Converting Two-Dimensional Objects to the Three- Dimensional Scene

Computer Technologies for Converting Two-Dimensional Objects to the Three- Dimensional Scene

Integrating time and the third spatial dimension in landscape structure analysis

Over the last decades, landscape metrics have been increasingly used to describe and analyse landscape structure. This article highlights some limitations of standard landscape structure analysis approaches and examines four major developments in this field: ways of integrating the height dimension of surface and vegetation into landscape metrics, the delineation of ‘meaningful’ landscape units comprising the relief, the problem of relating pattern and scale, and the challenges posed by the analysis of the temporal dimension of landscapes. We demonstrate that (1) the integration of height information and gradients into the approach of landscape metrics is both necessary and possible by means of using digital elevation models from remote sensing and novel analysis techniques, (2) the delineation of 3-D landscape units has enormous potential and (3) there are useful methodical extensions for two-dimensional objects in spatiotemporal investigations of landscapes, namely for analysing land use change and for exploring the interrelations between landscape diversity and species diversity.

A two-dimensional Segmented Boundary Algorithm for complex moving solid boundaries in Smoothed Particle Hydrodynamics

A Segmented Boundary Algorithm (SBA) is proposed to deal with complex boundaries and moving bodies in Smoothed Particle Hydrodynamics (SPH). Boundaries are formed in this algorithm with chains of lines obtained from the decomposition of two-dimensional objects, based on simple line geometry. Various two-dimensional, viscous fluid flow cases have been studied here using a truly incompressible SPH method with the aim of assessing the capabilities of the SBA. Firstly, the flow over a stationary circular cylinder in a plane channel was analyzed at steady and unsteady regimes, for a single value of blockage ratio. Subsequently, the flow produced by a moving circular cylinder with a prescribed acceleration inside a plane channel was investigated as well. Next, the simulation of the flow generated by the impulsive start of a flat plate, again inside a plane channel, has been carried out. This was followed by the study of confined sedimentation of an elliptic body subjected to gravity, for various density ratios. The set of test cases was completed with the simulation of periodic flow around a sunflower-shaped object. Extensive comparisons of the results obtained here with published data have demonstrated the accuracy and effectiveness of the proposed algorithms, namely in cases involving complex geometries and moving bodies.

The Effect of View Independence in a Collaborative AR System

In this paper we describe a system for remote collaboration using Augmented Reality (AR) that supports view independence. The system was designed to allow a remote user to assist a local user in an object placement task. The remote helper can navigate the local user's scene independently from the local user by using a three-dimensional reconstruction of the environment. The remote user can also place virtual annotations in the scene that the local user views through a head mounted display. The system tracks the position of key physical objects and the local user's head pose, displaying both to the remote user. A key advantage of this system compared to other collaborative AR interfaces is that it allows the remote expert to have an independent view into the shared task space. A user study was performed using this system with the users completing a simple mostly two-dimensional object placement task. It was designed to test how the amount of remote view independence affected collaboration. Four conditions were used with varying degrees of view independence. It was found that increased view independence led to faster task completion time, more confidence from users, and a decrease in the amount of time spent communicating verbally during the task. However, varying the view independence did not significantly change the accuracy of the placement of objects. The implications of the results are discussed along with directions for future research.

A thermophysical study on the freeze drying of wooden archaeological artifacts

Abstract The protection of unearthed waterlogged archaeological artifacts is a heavy task when large-scale construction is carried out in today's China. Freeze drying offers an efficient way for preserving wooden artifacts. In order to rationally design the freeze drying process, thermophysical studies were carried out in this paper. The measurements of water vapor diffusion coefficient and thermal conductivity were made. The impacts of cooling velocity and grain orientation on effective diffusion coefficient of water vapor, D, in dried wood were investigated. At low cooling velocity, 0.2 K/min, D was (4.8 ± 0.4) × 10 −4 m 2 /s in parallel grain direction, or (1.9 ± 0.4) × 10 −4 m 2 /s in perpendicular grain direction; at higher cooling velocity, 3.0 K/min, D was (4.3 ± 0.2) × 10 −4 m 2 /s in parallel grain direction, or (1.2 ± 0.1) × 10 −4 m 2 /s in perpendicular grain direction. The thermal conductivity of the dried sample was in the range of 0.78–1.06 W/(m·K). With the values attained, one-dimensional pseudo-steady analysis were made for the primary drying process of a cylinder and a flat slab. It was found that the process was mass-transfer controlled and the difference between surface temperature and sublimation temperature was very limited. Thus only mass transfer equation needed to be solved with assumption of constant sublimation temperature. The primary drying of a two-dimensional object was also simulated to predict the time required. Monitoring the surface temperature of each artifact and handling artifacts with similar drying time in a batch are proposed for the freeze drying of archaeological artifacts. The freeze-dried wooden artifacts by the authors yielded very small deformations.