3D Solution Research Articles

Is the Moyal equation for the Wigner function a quantum analogue of the Liouville equation?

The Moyal equation describes the evolution of the Wigner function of a quantum system in the phase space. The right-hand side of the equation contains an infinite series with coefficients proportional to powers of the Planck constant. There is an interpretation of the Moyal equation as a quantum analogue of the classical Liouville equation. Indeed, if one uses the notion of the classical passage to the limit as the Planck constant tends to zero, then formally the right-hand side of the Moyal equation tends to zero. As a result, the Moyal equation becomes the classical Liouville equation for the distribution function. In this paper, we show that the right side of the Moyal equation does not explicitly depend on the Planck constant, and all terms of the series can make a significant contribution. The transition between the classical and quantum descriptions is related not to the Planck constant, but to the spatial scale. For a model quantum system with a potential in the form of a «quadratic funnel», an exact 3D solution of the Schrödinger equation is found and the corresponding Wigner function is constructed in the paper. Using trajectory analysis in the phase space, based on the representation of the right-hand side of the Moyal equation, it is shown that on the spatial microscale there is an infinite number of «trajectories» of the particle motion (thereby the concept of a trajectory is indefinite), and when passing to the macroscale, all «trajectories» concentrate around the classical trajectory.

Modeling and Experimental Validation of CFRP–Metal Joints Utilizing 3D Additively Manufactured Anchors

Abstract The joining techniques between carbon fiber reinforced polymer (CFRP) and metal are of great importance in many areas of structural mechanics where the optimization of weight, rigidity, and strength is a necessity (such as aeronautics, vehicles, energy generation, and biomechanics). As a result, several types of metal–composite joints have been manufactured using different methods, with the 3D metal anchor solution attracting significant attention. This study evaluates different anchor geometries applied to single lap joints through preliminary finite element method (FEM) simulations and experimental validation on joints between CFRP and Inconel 625 produced via a laser beam powder bed fusion (LB-PBF) additive process. The models proposed increase in complexity. The homogenization process is employed to determine the equivalent properties of the joint region that is occupied by metal anchors and CFRP. The model also supports topology parametrization to assess the impact of anchor geometry on structural properties. The study provides experimental validation of joint strength under tensile load for various anchoring surface topologies.

Deep Learning-based Human Pose Estimation: A Survey

Human pose estimation aims to locate the human body parts and build human body representation (e.g., body skeleton) from input data such as images and videos. It has drawn increasing attention during the past decade and has been utilized in a wide range of applications including human-computer interaction, motion analysis, augmented reality, and virtual reality. Although the recently developed deep learning-based solutions have achieved high performance in human pose estimation, there still remain challenges due to insufficient training data, depth ambiguities, and occlusion. The goal of this survey article is to provide a comprehensive review of recent deep learning-based solutions for both 2D and 3D pose estimation via a systematic analysis and comparison of these solutions based on their input data and inference procedures. More than 260 research papers since 2014 are covered in this survey. Furthermore, 2D and 3D human pose estimation datasets and evaluation metrics are included. Quantitative performance comparisons of the reviewed methods on popular datasets are summarized and discussed. Finally, the challenges involved, applications, and future research directions are concluded. A regularly updated project page is provided: https://github.com/zczcwh/DL-HPE .

Structured-Light Scanning and Metrological Analysis for Archaeology: Quality Assessment of Artec 3D Solutions for Cuneiform Tablets

This paper deals with a metrological and qualitative evaluation of the Artec 3D structured-light scanners: Micro and Space Spider. As part of a larger European project called ITSERR, these scanners are tested to reconstruct small archaeological artefacts, in particular cuneiform tablets with different dimensions. For this reason, Micro and Space Spider are compared in terms of the entire workflow, from preparatory work to post-processing. In this context, three cuneiform replica tablets will serve as examples on which the Artec scanners will have to prove their worth. Metric analyses based on distance maps, RMSe calculations and density analyses will be carried out to understand metrological differences between these tools. The creation of 3D models of cuneiform tablets is the first step in developing a virtual environment suitable for sharing the archaeological collection with collaborators and other users. The inclusion of semantic information through specific ontologies will be the next step in this important project.

Three-dimensional unsteady state solution of multilayered saturated anisotropic finite media subjected to point source

The three-dimensional (3D) unsteady state solution of a saturated anisotropic finite porous medium due to a point source is presented in this paper. First, Laplace transform is introduced to address the governing equations of anisotropic poroelasticity. Next, the eigen equation method and the modified pseudo-Stroh formalism are used to obtain the transient solution for homogeneous saturated finite media. Then, the propagation matrix method is used to address the corresponding multilayered porous elastic media, and the 3D unsteady state solution of the layered porous medium subjected to a point source is obtained. The solution for a finite porous foundation is presented to demonstrate the use of the closed form solution. The numerical results of a homogeneous foundation due to an internal time-dependent point source are given. Two different point sources are used to show the transient responses of the proposed method. By comparing with those obtained by the finite element method, the accuracy of the proposed method has been proved. Meanwhile, the influence of the depth of the point source on the hydromechanical responses of the homogeneous foundation is discussed. Finally, the transient response of an anisotropic sandwich foundation due to a point source at different depths is investigated. These numerical examples prove the feasibility of the transient 3D solution. The closed form solution presented in this paper can provide help for 3D transient fluid-deforming coupling analysis of laminated porous media.

Mathematical Modeling of Single and Phase Autowaves in a Ferrocolloid

This paper describes a mathematical model of an autowave process in a cell with a ferrocolloid. The model is a system of differential coupled equations of the second order and differs from the previously presented model in terms of its original boundary conditions. The mathematical modeling of autowaves presented in this work constitutes an innovative approach, since the characteristics of the wave process are not initially included in the model but the model demonstrates a wave motion. A 2D solution of the model, which shows the correctness of the described mechanism of the autowave process, i.e., the recharging of magnetic particles in dense near-electrode layers formed near the electrodes under the influence of an electric field, is obtained. The propagation of single and phase autowaves is demonstrated in a computer experiment.

Adaptable 2D to 3D Stereo Vision Image Conversion Based on a Deep Convolutional Neural Network and Fast Inpaint Algorithm.

Algorithms for converting 2D to 3D are gaining importance following the hiatus brought about by the discontinuation of 3D TV production; this is due to the high availability and popularity of virtual reality systems that use stereo vision. In this paper, several depth image-based rendering (DIBR) approaches using state-of-the-art single-frame depth generation neural networks and inpaint algorithms are proposed and validated, including a novel very fast inpaint (FAST). FAST significantly exceeds the speed of currently used inpaint algorithms by reducing computational complexity, without degrading the quality of the resulting image. The role of the inpaint algorithm is to fill in missing pixels in the stereo pair estimated by DIBR. Missing estimated pixels appear at the boundaries of areas that differ significantly in their estimated distance from the observer. In addition, we propose parameterizing DIBR using a singular, easy-to-interpret adaptable parameter that can be adjusted online according to the preferences of the user who views the visualization. This single parameter governs both the camera parameters and the maximum binocular disparity. The proposed solutions are also compared with a fully automatic 2D to 3D mapping solution. The algorithm proposed in this work, which features intuitive disparity steering, the foundational deep neural network MiDaS, and the FAST inpaint algorithm, received considerable acclaim from evaluators. The mean absolute error of the proposed solution does not contain statistically significant differences from state-of-the-art approaches like Deep3D and other DIBR-based approaches using different inpaint functions. Since both the source codes and the generated videos are available for download, all experiments can be reproduced, and one can apply our algorithm to any selected video or single image to convert it.

Limit behaviors of weak solution and statistical solution for 3D Bénard-α model

This paper is concerned with weak solutions and statistical solutions of the Bénard-α model in three-dimensional domain. Based on uniform estimates with respect to the regularization parameter α, we first prove that a sequence of weak solutions of the 3D Bénard-α model converges to a counterpart of the classical Bénard model in the given topology as the regularization parameter α vanishes. Applying the Topsoe lemma on the appropriate trajectory space with some special topological properties, we further show that a sequence of α-Vishik-Fursikov measures of the 3D Bénard-α model converges to a Vishik-Fursikov measure of the classical Bénard model as α decreases to zero.

A simple meshfree method based on Trefftz attitude for 2D and 3D elasticity problems

A simple meshfree method is developed for the solution of 2D and 3D elasticity problems in potentially heterogeneous media. The rationale of the method follows that of Trefftz approaches to apply the Partial Differential Equation (PDE) and the boundary conditions in separate steps, while the basis functions can satisfy the PDE. The solution domain is discretized by a regular nodal grid including DOFs as the displacement components. The boundary is also discretized by some boundary points independent from the nodes, making the method applicable for arbitrarily shaped domains without imposing irregularity to the nodal grid. Each node corresponds to a cloud that contains some of its adjacent nodes as well. The overlap of the clouds integrates the displacement and stress components throughout the domain. The governing elasticity PDEs in heterogeneous media have non-constant coefficients, preventing Trefftz techniques to be applicable. The present method, based on equilibrated basis functions, satisfies the PDE in weighted residual approach to extract some bases capable of its approximately satisfaction. The weighting may remove the boundary integrals, so the boundary conditions are simply collocated. The integrals are composed by combination of 1D predefined ones, then removing the numerical quadrature from the solution procedure.

Innovative NDT Technique, for a More Productive Surface Damage Inspection

The challenges faced by NDT service companies are becoming increasingly prominent. First, these issues take place in a market comprised of old, rapidly aging infrastructure, which causes an increased demand for inspection. Moreover, there is a shortage of skilled labor as well as the increased departures of retiring experienced technicians, which puts a lot of pressure on service companies to keep pace with projects and honor their contracts. One way or the other, productivity gains will need to be realized to answer the growing demand with less manpower. This article will discuss surface damage NDT applications resolved with a 3D scanner. 3D scanning solutions involve only a short learning curve and require fewer certifications than traditional techniques. They are also much faster than manual tools, offering rapid field deployment and instant reports that are directly accessible in the field. The file format of the inspection results generates metrology-grade accuracy, traceable data over time, as well as human-independent results that eliminate measurement variations and ambiguity in result interpretation. This article will also introduce this relatively new technique in terms of performance and limitations, then it will present an overview of the different applications available in all traditional NDT industries such as oil & gas, aerospace, power generation, and more.

Printed Electronics in Radiofrequency Energy Harvesters and Wireless Power Transfer Rectennas for IoT Applications

AbstractThe Internet of Things is currently one of the fastest‐growing branches in electronics. The development of energy storage systems and the miniaturization of dedicated printed circuit boards significantly influence that growth. However, the need for batteries and traditional printed circuit boards still limits devices' minimum size, weight, and cost, narrowing the application area. Energy harvesters and wireless power transfer systems fabricated with printed electronics can significantly reduce such devices' weight, size, and cost. Printed electronics technology provides scalable tools for many electronics applications, shortening the validation time and enabling new low‐cost or disposable solutions on lightweight and flexible substrates embedded inside 3D printed structures and directly on device housings. Energy harvesting and wireless power transfer systems in electronic devices can provide enough power to minimize battery capacity and size or even eliminate the need for batteries in low‐power applications. This review presents an adaptation of printed electronics technology in the fabrication of radio frequency energy harvesters and wireless power transfer rectennas for IoT applications. Last, perspectives for development towards greater integration with microsystems, transient electronics with ecofriendly materials, adaptation for next‐generation telecommunication systems, and 3D structural electronics solutions are briefly discussed.

Three-dimensional thermoelastic analysis of orthotropic laminated cylindrical shells subjected to uniformly localized thermal boundary conditions

Accurate evaluation of three-dimensional (3D) thermal-elastic analysis of laminated cylindrical shells under different loads has a significant impact on their safety design. In this study, we present a 3D thermoelastic solution of laminated orthotropic cylindrical shells subjected to uniformly localized thermal boundary conditions. For a homogeneous orthotropic layer, a thinning layer approach is introduced to deal with the heat conduction equation and the elastic equation. Based on the eigenequation method and pseudo-Stroh formalism, general solutions for physical quantities of a homogeneous layer are derived. The propagator matrix method is used to deal with multilayered media. A closed form solution for the laminated cylindrical shells is obtained. A numerical example of a 3-layered cylindrical shell subjected to convective heat transfer boundary conditions is presented to verify the solutions’ correctness. An excellent convergence of the current approach is found and the physical quantities predicted by the current method agree well with the numerical results by the finite element method. Finally, the numerical solutions of a 3-layered orthotropic cylindrical shell subjected to uniformly localized thermal boundary conditions are obtained by the current method. The closed form solution presented in this article can be used for 3D thermoelastic analysis of laminated cylindrical shells under complex boundary conditions.

Fast 3D Mapping Solution with UAV

Abstract The photogrammetric method of 3D mapping uses Structure from Motion (SfM) algorithm, where 3D structures of a scene are created from 2D sets of data taken from multiple angles. This 3D mapping process is used in many advanced and important applications in the digital and robotics industry. The use of omnidirectional camera along with UAV for this photogrammetric process allows faster data acquisition and data processing to construct 3D structures compared to traditional method. However, the metric accuracy of spherical photogrammetry is relatively less compared to traditional framed camera photogrammetry. Hence, this research will focus on improving metric accuracy of spherical photogrammetry by enhancing SfM algorithm for the purpose of providing an enhanced and value-added fast 3D mapping solution using UAV. The research was conducted at 4 main levels. 1) Data acquisition phase, where the 360-degree camera with GPS tracker are attached to a UAV, and it is used to collect different sets of images at different heights and angles. 2) Camera calibration, for the purpose of identifying the camera intrinsic and extrinsic. These 2 parameters are crucial in feature detection and camera position estimation. 3) Data processing phase, where the collected data would be processed through the enhanced SfM algorithm to create the 3D structures. 4) Data analysis phase, where the 3D model created from enhanced SfM algorithm would be compared against a reference 3D model created by commercial software. However, the results attained were not as expected due to undesired feature detection process. This research is expected to help geographical and land surveyors to conduct surveys at a faster, more efficient and at a higher accuracy. A practical use case of this solution is to survey the terrain of an area under natural disaster, accurately and faster for search and rescue missions.

Rational understanding of viscoelastic drop impact dynamics on porous surfaces considering rheological properties

Understanding of viscoelastic drop impact on porous solid surfaces emerges as the essential physics for broad industrial and biological systems. However, there have been few studies concerning the post-drop impact transition considering rheological properties and dynamics. Here, we report the post-impact dynamics of viscoelastic drops on porous mesh surfaces using experimental and theoretical analyses. Five concentrations of highly viscous polymer solutions with shear-thinning and viscoelastic characteristics exhibit different rheological properties (viscosity, storage, loss moduli, etc.). These changes in the rheological features result in four distinguishable impact dynamics on two-dimensional mesh surfaces. Viscoelastic drops that exhibit viscoelastic solid properties (storage modulus > loss modulus) resulted in combined elastic solid-like motions and viscous fluid-like motions depending on the impact velocity and anti-penetration effects (such as capillary pressure and yield stress). Meanwhile, decreases in the viscoelastic fluid properties resulted in monotonous viscosity-dominant behaviors. A pressure-balance equation was proposed to theoretically predict the filament column penetration length of viscoelastic solid drops. The theoretical results correlated with the experimentally measured values until necking occurred in the filament column. We believe that this study on viscoelastic drop impact dynamics can shed light on future applications that involve various mechanical behaviors of non-Newtonian fluid drops, such as 3D printing, coating, bio-fluid treatments, and polymeric solutions.

A retrospective analysis and systematic review of the areas of entertainment computing and persuasive technologies for health

The areas of entertainment computing and persuasive technologies are interdisciplinary fields that have gained increasing attention in the last decades. Health is one of the domains that has leveraged the benefits of fun to improve the results of its technology-enabled interventions. Previous work has reviewed the area of health entertainment from many different perspectives; however, an integrative analysis across disciplines (health sciences and computer science and engineering) throughout the development and validation cycle of technologies in this domain is missing. Having such an in-depth retrospective analysis would shed light on how research on entertainment computing and persuasive technologies for health has evolved, acknowledging its contributions, recognizing its strengths and limitations, and, as a result, allowing for the definition of ways forward. This paper engages in an unprecedented systematic review of the work produced between 2004 and 2017 in this area. From an initial total of 10,350 retrieved results, a total of 1,307 full-texts were included in this review and were thoroughly examined to gain a retrospective understanding of the type of studies that have been produced. Among others, this systematic review reports on the trends, venues of publication, and the characteristics of the studies including methodologies, sample characteristics, study design, the type of solutions produced, the conditions and domains of application, and the purpose of the studies. Results show that there is a growing body of research in the area, with most studies being published in roughly the same venues, and where the lion's share of solutions fall into the area of health rehabilitation and motor conditions. With regards to the most addressed health domains, our review shows that most solutions produced are aimed at stroke and fitness, followed by balance training. Most studies (82.3%) are conducted with their target population, mostly adults (18–49 y), and are conducted either in the lab or in clinical settings. However, the median sample size of the studies has remained stable (N = 20) in the last decades. Regarding technology, 2D and 3D solutions are equally used, and most systems employ movement sensors and are single-user. Finally, only 21.4% of the studies are performed using validated instruments.

A meshfree method for the solution of 2D and 3D second order elliptic boundary value problems in heterogeneous media

We propose a simple meshfree method for two-dimensional and three-dimensional second order elliptic boundary value problems in heterogeneous media based on equilibrated basis functions. The domain is discretized by a regular nodal grid, over which the degrees of freedom are defined. The boundary is also discretized by simply introducing some boundary points over it, independent from the domain nodes, granting the method the ability of application for arbitrarily shaped domains without the drawback of irregularity in the nodal grid. In heterogeneous media, the governing Partial Differential Equation (PDE) has non-constant coefficients for the partial derivatives, preventing Trefftz-based techniques to be applicable. The proposed method satisfies the PDE independent from the boundary conditions, as in Trefftz approaches. Meanwhile, by applying the weak form of the PDE instead of the strong form through weighted residual integration, the inconvenience of variable coefficients shall be resolved, since the bases will not need to analytically satisfy the PDE. The weighting in the weak form integrals is such that the boundary integrals vanish. The boundary conditions are thus collocated over the defined boundary points. Domain integrals break into algebraic combination of one-dimensional pre-evaluated integrals, thus omitting the numerical integration from the solution process. Each node corresponds to a local sub-domain called cloud. The overlap between adjacent clouds ensures integrity of the solution and its derivatives throughout the domain, an advantage with respect to C0 formulations.

An Application of Softsign Function (SF) Filter to Low-Latitude Aeromagnetic Data of Tafawa-Balewa Area, Northern Nigeria for Geostructural Mapping and Tectonic Analysis

A recently proposed edge detection technique – Softsign Function (SF) filter was applied to a synthetic magnetic data to illustrate its application. It was then applied in combination with 3D Euler deconvolution and 2D magnetic modelling techniques to the low-latitude aeromagnetic data of Tafawa-Balewa Area, Northern Nigeria, aimed at subsurface geostructural mapping and tectonic analysis of the study area. This was corroborated with mapping and analysis of surface lineaments from Landsat-9 image of the study area. The SF filter depicted edges of magnetic sources from the synthetic magnetic and aeromagnetic data as distinct peaks. The 3D Euler deconvolution solutions and 2D magnetic model showed two dominant depth ranges ∼ 10 m to ∼ 400 m (D1) and ∼ 400 m to ∼ 1000 m (D2) of magnetic sources. The subsurface and surface lineaments from the aeromagnetic data and Landsat-9 image, respectively, fairly agreed in location, trends, even distribution, and density. The trends of mapped lineaments are majorly ENE – WSW direction, and the minor trends are WNW – ESE, NE – SW, NNW – SSE, NNE – SSW, and NW – SE directions. These linear structures, consistent with regional tectonics, are suspected to be strike-slip faults generated by the conjugate system of strike-slip NE – SW and NW – SE faults, including the Romanche and Chain fault systems, produced by the oceanic-continental transcurrent movements which affected the Nigerian basement complex. Explicitly, Softsign Function (SF) filter is a valuable edge detection technique in mapping geological structures from a real low-latitude aeromagnetic data reduced to the geomagnetic equator for tectonic analysis.

Modeling of solidification process during multi-track laser cladding with 3D cellular automata coupling gas-liquid interface tracking and solute suppression nucleation

Modeling of solidification process during multi-track laser cladding with 3D cellular automata coupling gas-liquid interface tracking and solute suppression nucleation

COVID-19 Detection from Cough Recordings Using Bag-of-Words Classifiers.

Reliable detection of COVID-19 from cough recordings is evaluated using bag-of-words classifiers. The effect of using four distinct feature extraction procedures and four different encoding strategies is evaluated in terms of the Area Under Curve (AUC), accuracy, sensitivity, and F1-score. Additional studies include assessing the effect of both input and output fusion approaches and a comparative analysis against 2D solutions using Convolutional Neural Networks. Extensive experiments conducted on the COUGHVID and COVID-19 Sounds datasets indicate that sparse encoding yields the best performances, showing robustness against various combinations of feature type, encoding strategy, and codebook dimension parameters.

A self-sustaining serpentinization mega-engine feeds the fougerite nanoengines implicated in the emergence of guided metabolism.

The demonstration by Ivan Barnes et al. that the serpentinization of fresh Alpine-type ultramafic rocks results in the exhalation of hot alkaline fluids is foundational to the submarine alkaline vent theory (AVT) for life's emergence to its 'improbable' thermodynamic state. In AVT, such alkaline fluids ≤ 150°C, bearing H2 > CH4 > HS--generated and driven convectively by a serpentinizing exothermic mega-engine operating in the ultramafic crust-exhale into the iron-rich, CO2> > > NO3--bearing Hadean ocean to result in hydrothermal precipitate mounds comprising macromolecular ferroferric-carbonate oxyhydroxide and minor sulfide. As the nanocrystalline minerals fougerite/green rust and mackinawite (FeS), they compose the spontaneously precipitated inorganic membranes that keep the highly contrasting solutions apart, thereby maintaining redox and pH disequilibria. They do so in the form of fine chimneys and chemical gardens. The same disequilibria drive the reduction of CO2 to HCOO- or CO, and the oxidation of CH4 to a methyl group-the two products reacting to form acetate in a sequence antedating the 'energy-producing' acetyl coenzyme-A pathway. Fougerite is a 2D-layered mineral in which the hydrous interlayers themselves harbor 2D solutions, in effect constricted to ~ 1D by preferentially directed electron hopping/tunneling, and proton Gröthuss 'bucket-brigading' when subject to charge. As a redox-driven nanoengine or peristaltic pump, fougerite forces the ordered reduction of nitrate to ammonium, the amination of pyruvate and oxalate to alanine and glycine, and their condensation to short peptides. In turn, these peptides have the flexibility to sequester the founding inorganic iron oxyhydroxide, sulfide, and pyrophosphate clusters, to produce metal- and phosphate-dosed organic films and cells. As the feed to the hydrothermal mound fails, the only equivalent sustenance on offer to the first autotrophs is the still mildly serpentinizing upper crust beneath. While the conditions here are very much less bountiful, they do offer the similar feed and disequilibria the survivors are accustomed to. Sometime during this transition, a replicating non-ribosomal guidance system is discovered to provide the rules to take on the incrementally changing surroundings. The details of how these replicating apparatuses emerged are the hard problem, but by doing so the progenote archaea and bacteria could begin to colonize what would become the deep biosphere. Indeed, that the anaerobic nitrate-respiring methanotrophic archaea and the deep-branching Acetothermia presently comprise a portion of that microbiome occupying serpentinizing rocks offers circumstantial support for this notion. However, the inescapable, if jarring conclusion is drawn that, absent fougerite/green rust, there would be no structured channelway to life.