2D Version Research Articles

Orbital and escape dynamics in barred galaxies – I. The 2D system

In this paper we use the two-dimensional (2D) version of a new analytical gravitational model in order to explore the orbital as well as the escape dynamics of the stars in a barred galaxy composed of a spherically symmetric central nucleus, a bar, a flat disk and a dark matter halo component. A thorough numerical investigation is conducted for distinguishing between bounded and escaping motion. Furthermore bounded orbits are further classified into non-escaping regular and trapped chaotic using the Smaller ALingment Index (SALI) method. Our aim is to determine the basins of escape through the two symmetrical escape channels around the Lagrange points $L_2$ and $L_3$ and also to relate them with the corresponding distribution of the escape rates of the orbits. We integrate initial conditions of orbits in several types of planes so as to obtain a more complete view of the overall orbital properties of the dynamical system. We also present evidence that the unstable manifolds which guide the orbits in and out the interior region are directly related with the formation of spiral and ring stellar structures observed in barred galaxies. In particular, we examine how the bar's semi-major axis determines the resulting morphologies. Our numerical simulations indicate that weak barred structures favour the formation of $R_1$ rings or $R_1'$ pseudo-rings, while strong bars on the other hand, give rise to $R_1R_2$ and open spiral morphologies. Our results are compared with earlier related work. The escape dynamics and the properties of the manifolds of the full three-dimensional (3D) galactic system will be given in an accompanying paper.

Adaptive viscous–inviscid interaction method for analysis of airfoils in ground effect

The behavior of an airfoil in ground proximity is significantly different from out of ground. Therefore, understanding the effect of proximity to ground can help determine its aerodynamic characteristics, which are important design parameters. In this paper, an accurate viscous–inviscid interacting method is investigated as an alternative method to computing heavy Navier–Stokes solution for utilizing in the surface effect zone. The inviscid part is modeled by a 2D panel method, and the viscous part is modeled by solving the integral form of the laminar and turbulent boundary layer equations. Validation of the incompressible 2D version of the written code (so-called WIGPMBL) is carried out against experimental and other numerical codes for different airfoil geometries at various Reynolds numbers. Various aspects of aerodynamic characteristics such as pressure distribution, lift and drag coefficient, transition and separation points of symmetric and asymmetric airfoils have been validated. Consequently, the assessments have verified that the present method has good accuracy for predicting the effect of surface proximity.

CUDA programs for solving the time-dependent dipolar Gross–Pitaevskii equation in an anisotropic trap

In this paper we present new versions of previously published numerical programs for solving the dipolar Gross-Pitaevskii (GP) equation including the contact interaction in two and three spatial dimensions in imaginary and in real time, yielding both stationary and non-stationary solutions. New versions of programs were developed using CUDA toolkit and can make use of Nvidia GPU devices. The algorithm used is the same split-step semi-implicit Crank-Nicolson method as in the previous version (R. Kishor Kumar et al., Comput. Phys. Commun. 195, 117 (2015)), which is here implemented as a series of CUDA kernels that compute the solution on the GPU. In addition, the Fast Fourier Transform (FFT) library used in the previous version is replaced by cuFFT library, which works on CUDA-enabled GPUs. We present speedup test results obtained using new versions of programs and demonstrate an average speedup of 12 to 25, depending on the program and input size.

Audiovisual Spatial Coherence for 2D and Stereoscopic-3D Movies

In movie theaters, sound sources such as dialog are often reproduced on the center loudspeaker without regard to the visual position on screen. Some sound engineers and researchers have suggested that spatial audiovisual coherence could improve the audience experience, especially for stereoscopic-3D (s-3D) movies. In the experiment described, subjects were asked to judge the suitability of several soundtracks for eight s-3D sequences. Depending on the soundtrack, sound sources could be more or less coherent in azimuth and depth. Results showed that sound suitability could be significantly improved for most of the sequences when coherence in azimuth was achieved. An improvement in the experience of depth was only observed with one sequence. When sequences were presented in nonstereoscopic (2D) version, there was no significant effect of stereoscopy. Subjects quickly became accustomed to azimuthal coherence, which improved sound suitability throughout the experiment. This suggests that the audience adaptation to a new cinematographic convention regarding spatialization of sound objects would not be a burden.

An Actively Controlled Shape-Morphing Compliant Microarchitectured Material

The purpose of this paper is to introduce a new kind of microarchitectured material that utilizes active control to alter its bulk shape through the deformation of its compliant elements. This new kind of microarchitectured material achieves its reconfigurable shape capabilities through a new control strategy that utilizes linearity and closed-form analytical tools to rapidly calculate the optimal internal actuation effort necessary to achieve a desired bulk surface profile. The kind of microarchitectured materials introduced in this paper is best suited for high-precision applications that would benefit from materials that can be programed to rapidly alter their surface or shape by small repeatable amounts in a controlled manner. Examples include distortion-correcting surfaces on which precision optics are mounted, airplane wings that deform to increase maneuverability and fuel efficiency, and surfaces that rapidly reconfigure to alter their texture. In this paper, the principles are provided for optimally designing 2D or 3D versions of the new kind of microarchitectured material such that they exhibit desired material property directionality. The mathematical theory is provided for modeling and calculating the actuation effort necessary to drive these materials such that their lattice shape comes closest to achieving a desired profile. Case studies are provided to demonstrate the utility of this theory and finite-element analysis (FEA) is used to verify the results.

Three‐dimensional gamma criterion for patient‐specific quality assurance of spot scanning proton beams

The purpose of this study was to evaluate the effectiveness of full three‐dimensional (3D) gamma algorithm for spot scanning proton fields, also referred to as pencil beam scanning (PBS) fields. The difference between the full 3D gamma algorithm and a simplified two‐dimensional (2D) version was presented. Both 3D and 2D gamma algorithms are used for dose evaluations of clinical proton PBS fields. The 3D gamma algorithm was implemented in an in‐house software program without resorting to 2D interpolations perpendicular to the proton beams at the depths of measurement. Comparison between calculated and measured dose points was carried out directly using Euclidian distance in 3D space and the dose difference as a fourth dimension. Note that this 3D algorithm faithfully implemented the original concept proposed by Low et al. (1998) who described gamma criterion using 3D Euclidian distance and dose difference. Patient‐specific proton PBS plans are separated into two categories, depending on their optimization method: single‐field optimization (SFO) or multifield optimized (MFO). A total of 195 measurements were performed for 58 SFO proton fields. A MFO proton plan with four fields was also calculated and measured, although not used for treatment. Typically three different depths were selected from each field for measurements. Each measurement was analyzed by both 3D and 2D gamma algorithms. The resultant 3D and 2D gamma passing rates are then compared and analyzed. Comparison between 3D and 2D gamma passing rates of SFO fields showed that 3D algorithm does show higher passing rates than its 2D counterpart toward the distal end, while little difference is observed at depths away from the distal end. Similar phenomenon in the lateral penumbra was well documented in photon radiation therapy, and in fact brought about the concept of gamma criterion. Although 2D gamma algorithm has been shown to suffice in addressing dose comparisons in lateral penumbra for photon intensity‐modulation radiation therapy (IMRT) plans, results here showed that a full 3D algorithm is required for proton dose comparisons due to the existence of Bragg peaks and distal penumbra. A MFO proton plan with four fields was also measured and analyzed. Sharp dose gradients exist in MFO proton fields, both in the middle of the modulation and toward the most distal layers. Decreased 2D gamma passing rates at locations of high dose gradient are again observed as in the SFO fields. Results confirmed that a full 3D algorithm for gamma criterion is needed for proton PBS plan's dose comparisons. The 3D gamma algorithm is implemented by an in‐house software program. Patient‐specific proton PBS plans are measured and analyzed using both 3D and 2D gamma algorithms. For measurements performed at depths with large dose gradients along the beam direction, gamma comparison passing rates using 2D algorithm is lower than those obtained with the full 3D algorithm.PACS number: 87.53.Bn, 87.53.Jw, 87.55.de, 87.55.kd, 87.55.ne, 87.55.Qr

Pierre3D: a 3D stochastic rockfall simulator based on random ground roughness and hyperbolic restitution factors

The use of dynamic computational methods has become indispensable for addressing problems related to rockfall hazard. Although a number of models with various degrees of complexity are available, model parameters are rarely calibrated against observations from rockfall experiments. A major difficulty lies in reproducing the apparent randomness of the impact process related to both ground and block irregularities. Calibration of rigorous methods capable of explicitly modeling trajectories and impact physics of irregular blocks is difficult, as parameter spaces become too vast and the quality of model input and observation data are insufficient. The model presented here returns to the simple “lumped-mass” approach and simulates the characteristic randomness of rockfall impact as a stochastic process. Despite similarities to existing approaches, the model presented here incorporates several novel concepts: (i) ground roughness and particle roughness are represented as a random change of slope angle at impact; (ii) lateral deviations of rebound direction from the trajectory plane at impact are similarly accounted for by perturbing the ground orientation laterally, thus inducing scatter of run-out directions; and (iii) a hyperbolic relationship connects restitution factors to impact deformation energy. With these features, the model is capable of realistically accounting for the influence of particle mass on dynamic behaviour. The model only requires four input parameters, rendering it flexible for calibration against observed datasets. In this study, we calibrate the model against observations from the rockfall test site at Vaujany in France. The model is able to reproduce observed distributions of velocity, jump heights, and runout at observation points. In addition, the spatial distribution of the trajectories and landing points has been successfully simulated. Different parameter sets have been used for different ground materials such as an avalanche channel, a forest road, and a talus cone. Further calibration of the new model against a range of field datasets is essential. This study is part of an extensive calibration program that is still in progress at this first presentation of the method, and focuses on fine-tuning the details of the stochastic process implemented both in two-dimensional (2D) and three-dimensional (3D) versions of the model.

Numerical study of contributions of shock wave and gas penetration toward induced rock damage during blasting

The authors present an improved version of continuum analysis 2D, a hybrid two-dimensional finite element-discrete element-smoothed particle program for modeling rock blasting. A modified formula governing the interaction of smoothed particles with discrete elements is presented, along with the results of numerical simulations involving detonations within jointed rock. PETN was modeled as the explosive, and Barre granite as the rock specimen. The borehole was simulated both with and without a thin copper lining. The purpose of the copper lining is to prevent gas from penetrating into the induced cracks within the rock, so that the shock wave’s contribution toward rock damage can be separated from that of the gas penetration. The results suggest that majority of the cracks are formed due to the shock wave propagating within the rock, whereas the gas penetration mostly separates the already-formed rock fragments and pushes them apart.

Comparative Proteomics of Amylolytic Strains of Bacillus subtilis and Bacillus licheniformis

Bacillus is known to be one of the most important sources of proteins with industrial applications. Not much is known about the local strains of this genus in Nigeria. This study aimed at investigating the comparative proteomics of the intracellular and extracellular proteins from B.subtilis and B. licheniformis to identify proteins of industrial importance. B. subtilis and B.licheniformis strains earlier isolated were reactivated and used in this study. The organisms were incubated at 37oC and 50oC. The intracellular and extracellular proteins were extracted from the cells. The proteomes were resolved using one dimensional sodium dodecyl sulphate polyacrylamide gel electrophoresis and two dimensional differential gel electrophoresis. The proteins were further analysed using Decyder 2D version 6.0 software and the selected spots were subjected to Trypsin digestion. The peptide‐fragments were eluted into Linear Trapped Quadrupole Mass Spectrometer (LTQ‐MS/MS) and the RAW files obtained were searched against the database of the B. subtilis and B. licheniformis fasta files. The results obtained revealed that B. subtilis at 37oC secreted alpha‐amylase and YmcB protein extracellularly while the prominent intracellular proteins were bacitracin synthetase and glutathione peroxidase. In contrast, the prominent extracellular proteins secreted by B. licheniformis at 37oC were leucine aminopeptidase precursor and bacitracin transport ATP binding proteins while the intracellular proteins at 37oC were homoserine‐O‐succinyl transferase and bacitracin transport ATP binding protein. B. licheniformis grew at 50oC and produced many proteins. It was concluded that B. licheniformis was a more versatile producer of industrial proteins.

Tendency towards sphericity symmetry of pebbles: The rate change of volume with surface

The primary effect of rocks and stones tending to erode towards sphericity symmetry can be identified with the rate change of volume with surface. Marble pebbles of various shapes and sizes are recorded and modeled mathematically as ellipsoids. The rate change of volume with surface dV/dA is computed for flat-shaped pebbles where the thickness dimension is assumed to be unity. Invoked is the hypothesis that the change of shape and size of pebbles can be characterized by a master curve derived from dA/dL, the 2D version of dV/dA. The sphericity symmetry is assumed to be concerned with the preference of roundness to slenderness regardless of the surface roughness, smoothness and the mineralogical composition. The erosiveness and abrasiveness of the surface and time effects can interact with sphericity, which is an issue beyond the scope of this work.

Student Gestures Aid Penetrative Thinking

ABSTRACTPenetrative thinking, or the ability to visualize and reason about the interior structure of an object based on what is visible on the surface, is critical for success in many science disciplines, especially the geosciences, where inferences about the Earth must be made from what can be seen on the surface. A growing body of research has shown that spatial thinking skills are related to achievement in the science, technology, engineering, and mathematics (STEM) disciplines; thus, improving such skills may enhance STEM learning. In the current study, we examined whether using gestures, embodied representations of three-dimensional (3D) spatial relationships, facilitates penetrative thinking. Participants in the gesture group used their hands to explain how they would build 3D versions of geologic block diagrams from flat layers of Play-Doh. Participants in the gesture-prohibited group were asked to explain verbally, without using their hands, how they would build 3D versions of geologic block diagrams. Participants in the gesture group showed improvement on the Geologic Block Cross-Sectioning Test (GBCT), an objective measure of penetrative thinking, while participants in the gesture-prohibited group did not. These results suggest that gesturing facilitates penetrative thinking, and we discuss them in the context of integrating gesture into science classrooms.

CaPaSIM statement of methods

In the present paper, the method for calculation of the dynamic pantograph–catenary interaction developed by the Royal Institute of Technology and the Swedish National Rail/Road administration (Trafikverket) is described and the results of the benchmark exercise are discussed. The method is based on the commercial Finite Element software ANSYS. The geometry of the catenary and pantograph is defined in a pre-processor, BARTRAD, developed by Trafikverket, and is automatically translated into an ANSYS model. Basically all types of catenary systems could be handled as well as different types of non-linearity. There are both 2D and 3D versions of the code existing. The results achieved in this first stage of the benchmark are well in line with the results from the other partners in the benchmark study

Visual discomfort while watching stereoscopic three-dimensional movies at the cinema.

This study investigates discomfort symptoms while watching Stereoscopic three-dimensional (S3D) movies in the 'real' condition of a cinema. In particular, it had two main objectives: to evaluate the presence and nature of visual discomfort while watching S3D movies, and to compare visual symptoms during S3D and 2D viewing. Cinema spectators of S3D or 2D films were interviewed by questionnaire at the theatre exit of different multiplex cinemas immediately after viewing a movie. A total of 854 subjects were interviewed (mean age 23.7 ± 10.9 years; range 8-81 years; 392 females and 462 males). Five hundred and ninety-nine of them viewed different S3D movies, and 255 subjects viewed a 2D version of a film seen in S3D by 251 subjects from the S3D group for a between-subjects design for that comparison. Exploratory factor analysis revealed two factors underlying symptoms: External Symptoms Factors (ESF) with a mean ± S.D. symptom score of 1.51 ± 0.58 comprised of eye burning, eye ache, eye strain, eye irritation and tearing; and Internal Symptoms Factors (ISF) with a mean ± S.D. symptom score of 1.38 ± 0.51 comprised of blur, double vision, headache, dizziness and nausea. ISF and ESF were significantly correlated (Spearman r = 0.55; p = 0.001) but with external symptoms significantly higher than internal ones (Wilcoxon Signed-ranks test; p = 0.001). The age of participants did not significantly affect symptoms. However, females had higher scores than males for both ESF and ISF, and myopes had higher ISF scores than hyperopes. Newly released movies provided lower ESF scores than older movies, while the seat position of spectators had minimal effect. Symptoms while viewing S3D movies were significantly and negatively correlated to the duration of wearing S3D glasses. Kruskal-Wallis results showed that symptoms were significantly greater for S3D compared to those of 2D movies, both for ISF (p = 0.001) and for ESF (p = 0.001). In short, the analysis of the symptoms experienced by S3D movie spectators based on retrospective visual comfort assessments, showed a higher level of external symptoms (eye burning, eye ache, tearing, etc.) when compared to the internal ones that are typically more perceptual (blurred vision, double vision, headache, etc.). Furthermore, spectators of S3D movies reported statistically higher symptoms when compared to 2D spectators.

Adaptive prediction filtering in t-x-y domain for random noise attenuation using regularized nonstationary autoregression

Many natural phenomena, including geologic events and geophysical data, are fundamentally nonstationary. They may exhibit stationarity on a short timescale but eventually alter their behavior in time and space. We developed a 2D [Formula: see text] adaptive prediction filter (APF) and further extended this to a 3D [Formula: see text] version for random noise attenuation based on regularized nonstationary autoregression (RNA). Instead of patching, a popular method for handling nonstationarity, we obtained smoothly nonstationary APF coefficients by solving a global regularized least-squares problem. We used shaping regularization to control the smoothness of the coefficients of APF. Three-dimensional space-noncausal [Formula: see text] APF uses neighboring traces around the target traces in the 3D seismic cube to predict noise-free signal, so it provided more accurate prediction results than the 2D version. In comparison with other denoising methods, such as frequency-space deconvolution, time-space prediction filter, and frequency-space RNA, we tested the feasibility of our method in reducing seismic random noise on three synthetic data sets. Results of applying the proposed method to seismic field data demonstrated that nonstationary [Formula: see text] APF was effective in practice.

СРАВНЕНИЕ МЕТОДОВ НАЧЕРТАТЕЛЬНОЙ ГЕОМЕТРИИ И 3D КОМПЬЮТЕРНОГО ГЕОМЕТРИЧЕСКОГО МОДЕЛИРОВАНИЯ ПО ТОЧНОСТИ, СЛОЖНОСТИ И ЭФФЕКТИВНОСТИ

Urgent educational problem of inconsistency of content of the course of descriptive geometry (DG) with the trends in the development of CAD and geometric simulation is considered. While the development is aimed at expanding the scope of computer 3D geometric simulation the teaching of descriptive geometry projection methods continues despite the fact that they are in no demand in practical applications. To compare the estimations of versions of solutions in descriptive geometry and 3D five specific problems of the nomination in descriptive geometry of All-Russian Olympiad 2014 are considered. They are the construction of sphere, tangent to the paraboloid; determining the points of intersection of the ellipse defined by the axes, with a circle (without the ellipse); finding the reference points of the ellipse section and its projections; construction of a tetrahedron by one projection of its face; as well as the defining the points of intersection of the circle with an elliptical cone. The detailed versions of solutions of descriptive geometry and 3D are given for each problem. The comparison of versions of the solution according to the geometrical accuracy is done. It is offered to estimate not an abstract accuracy which corresponds to constructions made by aperfect caliper and a ruler but the real accuracy independently of methods of its achievement. It’s shown that with the computer realization of both variants their real accuracy is either equal or 3D is much better than DG. The estimation of the complexity of task solutions is given. The amount of information needed for the solution is taken as a criterion. The author makes the conclusion that generally 3D versions are easier than DG. The examples show that 3D solutions can be easily supplemented with researches of a solvable problem. Much higher visualization, accessibility and universality of 3D versions are highlighted. The author makes the conclusion about much higher general effectiveness of computer 3D variants and methods of solving the structural problems and the necessity of transfer to new training course of 3d theory. Keywords: descriptive geometry, computer graphics, 3D modeling, structural problems, geometrical accuracy, complexity and effectiveness of structural problems.

Modeling evolution of spatially distributed bacterial communities: a simulation with the haploid evolutionary constructor

BackgroundMultiscale approaches for integrating submodels of various levels of biological organization into a single model became the major tool of systems biology. In this paper, we have constructed and simulated a set of multiscale models of spatially distributed microbial communities and study an influence of unevenly distributed environmental factors on the genetic diversity and evolution of the community members.ResultsHaploid Evolutionary Constructor software http://evol-constructor.bionet.nsc.ru/ was expanded by adding the tool for the spatial modeling of a microbial community (1D, 2D and 3D versions). A set of the models of spatially distributed communities was built to demonstrate that the spatial distribution of cells affects both intensity of selection and evolution rate.ConclusionIn spatially heterogeneous communities, the change in the direction of the environmental flow might be reflected in local irregular population dynamics, while the genetic structure of populations (frequencies of the alleles) remains stable. Furthermore, in spatially heterogeneous communities, the chemotaxis might dramatically affect the evolution of community members.

Crystal Image Analysis Using 2D Synchrosqueezed Transforms

We propose efficient algorithms based on a band-limited version of 2D synchrosqueezed transforms to extract mesoscopic and microscopic information from atomic crystal images. The methods analyze atomic crystal images as an assemblage of nonoverlapping segments of 2D general intrinsic mode type functions, which are superpositions of nonlinear wave-like components. In particular, crystal defects are interpreted as the irregularity of local energy; crystal rotations are described as the angle deviation of local wave vectors from their references; the gradient of a crystal elastic deformation can be obtained by a linear system generated by local wave vectors. Several numerical examples of synthetic and real crystal images are provided to illustrate the efficiency, robustness, and reliability of our methods.

A deterministic computational model for the two dimensional electron and photon transport

A deterministic (non-statistical) two dimensional (2D) computational model describing the transport of electron and photon typical of space radiation environment in various shield media is described. The 2D formalism is casted into a code which is an extension of a previously developed one dimensional (1D) deterministic electron and photon transport code. The goal of both 1D and 2D codes is to satisfy engineering design applications (i.e. rapid analysis) while maintaining an accurate physics based representation of electron and photon transport in space environment. Both 1D and 2D transport codes have utilized established theoretical representations to describe the relevant collisional and radiative interactions and transport processes. In the 2D version, the shield material specifications are made more general as having the pertinent cross sections. In the 2D model, the specification of the computational field is in terms of a distance of traverse z along an axial direction as well as a variable distribution of deflection (i.e. polar) angles θ where −π/2<θ<π/2, and corresponding symmetry is assumed for the range of azimuth angles (0<φ<2π). In the transport formalism, a combined mean-free-path and average trajectory approach is used. For candidate shielding materials, using the trapped electron radiation environments at low Earth orbit (LEO), geosynchronous orbit (GEO) and Jupiter moon Europa, verification of the 2D formalism vs. 1D and an existing Monte Carlo code are presented.

Instabilities of collisionless current sheets revisited: The role of anisotropic heating

In this work, we investigate the influence of the anisotropic heating on the spontaneous instability and evolution of thin Harris-type collisionless current sheets, embedded in antiparallel magnetic fields. In particular, we explore the influence of the macroparticle shape-function using a 2D version of the PIC code ACRONYM. We also investigate the role of the numerical collisionality due to the finite number of macroparticles in PIC codes. It is shown that it is appropriate to choose higher order shape functions of the macroparticles compared to a larger number of macroparticles per cell. This allows to estimate better the anisotropic electron heating due to the collisions of macroparticles in a PIC code. Temperature anisotropies can stabilize the tearing mode instability and trigger additional current sheet instabilities. We found a good agreement between the analytically derived threshold for the stabilization of the anisotropic tearing mode and other instabilities, either spontaneously developing or initially triggered ones. Numerical effects causing anisotropic heating at electron time scales become especially important for higher mass ratios (above mi/me=180). If numerical effects are carefully taken into account, one can recover the theoretical estimated linear growth rates of the tearing instability of thin isotropic collisionless current sheets, also for higher mass ratios.

Dielectric breakdown model for polymer films

This paper describes a modified dielectric breakdown model (mDBM), to predict breakdown pathways in polymer films taking into consideration trapped charge and gaseous voids. Modeling components include: (1) accurate boundary integral equation method (BIEM) based on Green function formulations for grid-less, non-orthogonal, Poisson growth; (2) treatment of kernel singularities; (3) matrix algebra for extensibility, reuse, and rapid iterative computation; and (4) Monte Carlo statistics with inverse probability integral for tree branch growth. 2D and 3D versions of mDBM have been successfully validated against known data and closed-form solutions, viz. charge and capacitance calculations with agreement to within 3% of the theoretical. The versatility of the models has been demonstrated by results of test cases for throughfilm breakdown in the presence of trapped charge, gaseous void, and combination of trapped charge and gaseous void.