Shape Deformation Research Articles

Speculation of salinity and heterogeneity for some dry and saturated sandstone rocks

Salinity and conductivity are related because dissolved ions increase both salinity and conductivity. The variation of heterogeneity can significantly affect the electrical properties of materials. The main change in electrical properties is related to the conductor concentration, but this change does not increase monotonically with the concentration due to heterogeneity. Sandstone samples were gathered parallel to the layer direction and perpendicular to it. Electrical parameters were obtained at room temperature at rates ranging from 42 Hz to 5 MHz for distinct salinities. Heterogeneity is carried out by deformation of the grain shapes and changes in the components and compositions of the material. Loading pressure will cause grain deflection (anisotropy), and electrical properties change as a consequence. Samples were measured in parallel and perpendicular layers of precipitation (for anisotropy and isotropy measurements) and at different salinities. When a layer is heterogeneous, the electrical characteristics change in both perpendicular directions. The effect of electrical characteristics increases as salinity concentration is increased.

Direct Method of Aerodynamic Shape Optimization For Supersonic Aircraft Design

The efficient direct optimization method for Supersonic Aircraft Design is presented. Aerodynamic drag and sonic boom signature parameters are used as the objective functions minimized under geometric and aerodynamic constraints. The method combines Newton based algorithm with Euler space-marching solver. The efficiency of the method is demonstrated on examples of two- and three-dimensional aerodynamic design. Nose shapes that ensure minimum wave drag for specified constraints on the overall size are defined. It is shown that the near-optimal axisymmetric noses have a flat forward face. The median surface of a complex plane form wing with minimal drag due to lift is constructed. The simplest shape deformation of the wing providing the main part of aerodynamic drag diminishing is established. To profile the aircraft wing and fuselage providing optimal sonic boom parameters approaches of theory for sonic boom propagation are included in the method. The initial shock intensity as the primary value of the pressure signature is minimized. The results obtained within the framework of the Eulers equations and simplified flow models are compared.

Thermal Postbuckling Characteristics Of Angle-ply Laminated Truncated Circular Conical Shells

Here, the nonlinear thermoelastic pre- and post-buckling characteristics of angle-ply laminated composite conical shells subjected to uniform temperature rise are studied using semi-analytical finite element approach. The finite element formulation is based on first-order shear deformation theory and field consistency principle. The nonlinear governing equations, considering geometric nonlinearity based on von Karman’s assumption for moderately large deformation, are solved using Newton-Raphson iteration procedure coupled with displace- ment control method to trace the prebuckling followed by postbuckling equilibrium path. The presence of asymmetric perturbation in the form of small magnitude load spatially proportional to the linear buckling mode shape is assumed to initiate the bifurcation of the shell deformation. The study is carried out to highlight the influences of semi-cone angle, ply-angles, number of layers and number of circumferential waves on the nonlinear prebuckling/postbuckling thermoelastic response of the laminated circular conical shells. The participation of axisymmetric and asymmetric modes in the total response of the shells is brought out through the deformation shape analysis.

Wing Shape Optimization Using FFD and Twist Parameterization

Optimization of wing shapes for aerodynamic performance is presented using a combination of particle swarm method and surrogate models. The wing shape deformations are parameterized using free form deformation together with wing twist. The developed strategy is applied to the lift-constrained drag minimization of Onera M6 wing.

Efficient reduction of vertex clustering using front tracking with surface normal propagation restriction

A significant computational expense and source of numerical errors in front tracking is the remeshing of the triangulated front, required due to distortion and compaction of the front following the Lagrangian advection of its vertices. Additionally, in classic front tracking, the remeshing of the front mesh is required not only due to the deformation of the front shape, but also because the vertices of the front are translated in the direction tangential to the front, induced by the front advection. We present the normal-only advection (NOA) front-tracking method with the aim of preventing the tangential motion of the front vertices and the associated vertex clustering, in order to reduce the number of remeshing operations required to retain a high-quality triangulated interface. To this end, we reformulate the velocity used to advect the front at each discrete front-vertex position. The proposed method is validated and tested against the classic front-tracking method, comparing volume conservation, shape preservation, computational costs, and the overall need for front remeshing, as well as experimental results for canonical interfacial flows. The presented results demonstrate that the NOA front-tracking method leads to a typical reduction of remeshing operations by 80% or more compared to the classic front-tracking method for well-resolved cases, and results in a smoother front mesh, which is essential for an accurate representation of the geometrical properties of the front. The volume conservation error is reduced by approximately one order of magnitude with the proposed method compared to the classic front-tracking method, at a similar computational cost.

A 2D numerical model of 3D concrete printing including thixotropy

Additive Manufacturing (AM) techniques are increasingly drawing interest in the construction sector since they can offer new architectural possibilities while improving the accuracy and the sustainability of the construction process. Among these techniques, 3D Concrete Printing (3DCP) is probably the most established and its future role in lowering the environmental impact of the building industry is under deep investigation. 3DCP main advantages, which are linked to the capacity of building optimized structural shapes, without the need for formworks and in very short times, are however still limited by the lack of knowledge and regulation. It is therefore necessary to provide designers with more advanced design tools to fully unlock the potential of 3DCP. This work presents a numerical model of 3DCP, which realistically simulates the extrusion and layer deposition phases. The model assumes that fresh concrete can be treated as a homogeneous viscous fluid. The problem is then governed by the Navier-Stokes equations, which are solved in a Lagrangian framework with the Particle Finite Element Method (PFEM). A Bingham law, modified to include thixotropic effects, is employed to accurately reproduce the material rheological behaviour at the early ages. The model is then applied to simulate a simple printing scenario, for which the fundamental experimental data is available in the literature, to assess the role of thixotropy in the printing process. The results show how thixotropy has a crucial effect in limiting the overall shape deformation and in avoiding the early compression failure of the bottom layers. In this view, the developed model can be applied to optimize the printing parameters with respect to the rheological properties and could also suggest how to improve the toolpath and the printing times for a given structure.

Structure-to-Shape Aortic 3-D Deformation Reconstruction for Endovascular Interventions

Fluoroscopy-guided endovascular interventions by using X-ray images are challenging. The catheter needs to be manipulated precisely inside the aorta, while only 2-D views from the X-ray fluoroscopy are currently used to help the surgeons. Because the catheter is operated in a 3-D space, a visualization of the deforming 3-D aorta will be useful as guidance for catheter manipulation. Existing 3-D reconstruction methods fall short in only focusing on the deformation reconstruction of the aortic 3-D centerline, or using additional prior knowledge of 3-D catheter position for estimating the aortic 3-D deformation. In this article, we propose a novel framework that reconstructs the aortic 3-D deformation by fusing a preoperative 3-D model and two intraoperative X-ray images. Different from existing methods, the proposed framework reconstructs aortic deformation using a coarse-to-fine pipeline by first reconstructing the aortic 3-D centerline and then reconstructing the 3-D shape. To obtain the accurate features for the fluoroscopic-based 3-D reconstruction, we extract semantic features from the X-ray images, and compute the distance field to efficiently calculate the 3-D–2-D nonrigid correspondence. Nonlinear least squares optimization is used to solve the deformation of both centerline and shape. The proposed framework is validated using phantom and patient datasets, whose results demonstrate improved efficiency and accuracy compared with the existing methods. This framework provides a valuable clinical tool for endovascular interventions.

Human-pose estimation based on weak supervision

BackgroundIn computer vision, simultaneously estimating human pose, shape, and clothing is a practical issue in real life, but remains a challenging task owing to the variety of clothing, complexity of deformation, shortage of large-scale datasets, and difficulty in estimating clothing style. MethodsWe propose a multistage weakly supervised method that makes full use of data with less labeled information for learning to estimate human body shape, pose, and clothing deformation. In the first stage, the SMPL human-body model parameters were regressed using the multi-view 2D key points of the human body. Using multi-view information as weakly supervised information can avoid the deep ambiguity problem of a single view, obtain a more accurate human posture, and access supervisory information easily. In the second stage, clothing is represented by a PCAbased model that uses two-dimensional key points of clothing as supervised information to regress the parameters. In the third stage, we predefine an embedding graph for each type of clothing to describe the deformation. Then, the mask information of the clothing is used to further adjust the deformation of the clothing. To facilitate training, we constructed a multi-view synthetic dataset that included BCNet and SURREAL. ResultsThe Experiments show that the accuracy of our method reaches the same level as that of SOTA methods using strong supervision information while only using weakly supervised information. Because this study uses only weakly supervised information, which is much easier to obtain, it has the advantage of utilizing existing data as training data. Experiments on the DeepFashion2 dataset show that our method can make full use of the existing weak supervision information for fine-tuning on a dataset with little supervision information, compared with the strong supervision information that cannot be trained or adjusted owing to the lack of exact annotation information. ConclusionsOur weak supervision method can accurately estimate human body size, pose, and several common types of clothing and overcome the issues of the current shortage of clothing data.

Manipulation of phonon states in ion traps by shortcuts to adiabaticity

Shortcuts to adiabaticity (STA) provides the possibility of high accuracy manipulation of phonon states in ion traps. We propose a scheme realized experimentally for manipulating phonon states using STA and confirmed its effectiveness through generating Fock states. Our results show that the duration of the STA manipulation of phonon states is 16 times faster than that of the adiabatic evolution, and the non-resonant excitation can be suppressed by laser bias frequency, which are confirmed by experimental results. Moreover, we also carried out an experimental research on the robustness of STA, showing good robustness respect to the pulse shape deformation, bias noises and stochastic noise. This might lead to a useful step toward realizing fast and noise-resistant quantum manipulation within current experimental capacity.

Cryogenic temperature deformation behavior and shape memory mechanism of NiTiFe alloy

The excellent shape memory properties of NiTiFe alloys make them a popular choice for tube connection components and actuators in the aerospace industry. However, in order to obtain these properties, the alloy must undergo pre-deformation at specific cryogenic temperatures to induce the martensitic phase transformation. Despite their widespread use, the deformation behavior and shape memory mechanism of NiTiFe alloys at cryogenic temperatures remain unclear. To address this, we conducted a study investigating the deformation behavior and shape memory mechanism of Ni47Ti50Fe3 alloy at temperatures ranging from −190 °C to 150 °C using tensile tests, free recovery tests, and EBSD analysis. Our findings suggest that the deformation behavior of NiTiFe alloy can be classified into four classes corresponding to different deformation mechanisms. At temperatures above the Md (−15 to −30 °C), dislocation slip and {114}B2 deformation twinning occur without reversible strain. However, reversible and irreversible strains occur simultaneously at temperatures between −50 to −90 °C. At temperatures ranging from −110 to −150 °C, the reorientation/detwinning of the R-phase, stress-induced martensitic phase transformation, and yield stage of martensite occur in sequence. When the deformation temperature is within the range of −165–190 °C, the reorientation/detwinning of martensite occurs during the stress platform stage, and irreversible strain occurs during the yield stage of martensite. The best shape memory effect of the NiTiFe alloy is observed at deformation temperatures near Mf (−180 °C). Moreover, the reverse phase transformation temperatures increase with the increasing deformation amounts, even without plastic deformation. The temperature-dependent deformation map of NiTiFe alloy was obtained based on the tests conducted in this study, from which the influence of deformation temperatures on the different critical stresses and the deformation mechanism under different temperature conditions can be determined.

Prediction of bubble shape deformation in aqueous solutions of short-chain alcohols

The behaviour of bubbles in aqueous solutions of short-chain alcohols depends significantly on the alcohol concentration. At low concentrations, alcohols act as surfactants and slow the rising velocity of the bubble, whereas at higher concentrations, primarily due to the internal arrangement at the molecular level, the desorption of molecules from the bubble surface is facilitated and the mobility of the bubble surface is increased. These factors significantly affect both bubble velocity and deformation. On the basis of experimental data (aqueous solutions of ethanol and propanol in the entire concentration range), two relations were proposed for the estimation of bubble deformation depending on the dimensionless Weber number. The model was successfully verified on an independent data set of the velocity and deformation of bubbles that rise in a stationary liquid.

Action-conditional implicit visual dynamics for deformable object manipulation

Manipulating volumetric deformable objects in the real world, like plush toys and pizza dough, brings substantial challenges due to infinite shape variations, non-rigid motions, and partial observability. We introduce ACID, an action-conditional visual dynamics model for volumetric deformable objects based on structured implicit neural representations. ACID integrates two new techniques: implicit representations for action-conditional dynamics and geodesics-based contrastive learning. To represent deformable dynamics from partial RGB-D observations, we learn implicit representations of occupancy and flow-based forward dynamics. To accurately identify state change under large non-rigid deformations, we learn a correspondence embedding field through a novel geodesics-based contrastive loss. To evaluate our approach, we develop a simulation framework for manipulating complex deformable shapes in realistic scenes and a benchmark containing over 17,000 action trajectories with six types of plush toys and 78 variants. Our model achieves the best performance in geometry, correspondence, and dynamics predictions over existing approaches. The ACID dynamics models are successfully employed for goal-conditioned deformable manipulation tasks, resulting in a 30% increase in task success rate over the strongest baseline. Furthermore, we apply the simulation-trained ACID model directly to real-world objects and show success in manipulating them into target configurations. https://b0ku1.github.io/acid/

Numerical study of vanadium redox flow battery with gradient porosity induced by electrode compression

In VRFBs with flow fields, the compression and deformation of the porous electrode are non-uniform due to the rib-channel patterns and part of electrode intrudes into the channel, making the transportation of active species within the battery more complex. The impact of non-uniform electrode compression on VRFB performance has not been fully investigated. In this study, a novel non-uniform compression model that incorporates the gradient porosity distribution resulting from electrode compression is proposed. This model aims to account for both the deformation of electrode shape and the non-uniformity of physical properties. The proposed non-uniform compression model surpasses the limitations of conventional uniform compression models by offering enhanced accuracy in predicting charge-discharge behavior and electrolyte flow dynamics. Specifically, this model effectively addresses the under-prediction of electrolyte flow and reactant supply encountered in traditional uniform compression models, while simultaneously preventing the over-prediction of concentration polarization. Increasing the CR has the benefit of reducing ohm and concentration polarization, but it increases pump power loss. Through a trade-off analysis between the advantages and disadvantages of CR, an optimized electrode CR of 28 % is identified, which exhibits the maximum system efficiency of 80.9 %. The proposed model can guide the design of VRFB when considering the influence of compressed electrode.

Fundamental Investigations of the Deformation Behavior of Single-Crystal Ni-Mn-Ga Alloys and Their Polymer Composites via the Introduction of Various Fields

To meet the great requirements of future technologies, such as robots, single-crystal (SC) Ni-Mn-Ga alloys and their composites were designed and investigated in this study. Ferromagnetic shape memory alloys (FSMAs) are promising materials for applications in high-speed actuators, which are core components of robots; however, there are some issues of embrittlement and small deformation strain. Therefore, in this work, we first prepared SC Ni-Mn-Ga alloys for fundamental investigations of the shape deformations under the application of different fields (e.g., compressive and magnetic fields). Second, the SC Ni-Mn-Ga alloys were integrated with polymers of epoxy resin or silicone rubber to solve the embrittlement problem. The obvious two-stage yielding and sudden intensifying of the magnetization both suggest martensite variant reorientation (MVR) under the compressive and magnetic fields, respectively. Micro-computed tomography (μCT) and an X-ray diffractometer were utilized for the observations of shape deformation brought about by the MVR of the SC Ni-Mn-Ga particles in the polymer matrix. Clear MVR and shape deformation could be found in the compressed composites.

Multi-Stimuli Responsive Soft Actuator with Locally Controllable and Programmable Complex Shape Deformations

Multi-Stimuli Responsive Soft Actuator with Locally Controllable and Programmable Complex Shape Deformations

The attractiveness of 4D printing in the medical field: Revealing scientific and technological advances in design factors and applications

Currently, there is an increasing demand in the medical field for low-cost, high-quality products as well as personalized solutions, and different manufacturing methods are being investigated to provide innovative solutions. Four-dimensional (4D) printing is a promising technology that could overcome the challenges associated with the applications of three-dimensional printing in regenerative medicine and biomedical devices. A revolution is expected in this regard, and it is essential to keep abreast of the latest developments. Under this context, the purpose of this paper is to reveal scientific and technological advances of 4D printing in the medical field using a competitive technology intelligence (CTI) methodology. To this end, publications were analyzed from the Scopus database between January 1, 2017, and May 9, 2023. The main trends were identified for both design factors and applications. In the first case, the following were considered: 4D printing methods, external stimuli, materials, mathematical models, and interaction mechanisms. In contrast, in the second case, the applications of 4D printing involved were considered: drug delivery systems, stents, and scaffolds. The obtained design factors results included improvements in mechanical properties of hydrogels by adding magnetic nanoparticles, biopolyurethane, and other materials, the development of cell-friendly bioprinting methods to print cellular structures, and the use of theoretical-experimental approaches to predict shape deformation of structures. While for applications, results included advances in the development of expandable drug delivery systems, fabrication of stents for the treatment of vascular and tracheal stenosis, and the design of scaffolds to treat cartilage defects and bone regeneration. This study provides insights to researchers, academics, and companies involved in research and development as well as innovation that are looking for new solutions to improve health by incorporating breakthrough technologies such as 4D printing.

Evaluation of sex dimorphism of the mandible with geometric morphometric analysis: conventional and reconstructed panoramic radiography study.

The purpose of the study was to investigate the mandible shape dimorphism between males and females both on conventional panoramic radiographs (cPR) and reconstructed panoramic radiographs obtained from cone beam computed tomography (rPR) with geometric morphometric method. Panoramic radiographs and cone beam computed tomography scans were performed on 33 males and 35 females with median age 23.0 (13.0-57.0) years old. The mandibular shape comparisons between genders were examined with Procrustes analysis, mandible shape classification analysis was made with principal component analysis and shape deformations were concluded from thin plate spline (TPS) analysis. Age had no statistically significant difference between gender (p = 0.580). For the shape of mandible on cPR and rPR, there were statistically significant differences between males and females (p = 0.002, p = 0.032, respectively). The shape variabilities of mandible on cPR for females were 0.054 and for males 0.053. The shape variabilities of mandible on rPR for females were 0.051 and for males 0.049. Both on cPR and rPR, the shape variability of the females' mandible was similar within their group, the shape variability of the males' mandible was similar within their group. In the examination of mandibular dimorphism in cPR, maximal deformations were seen in the region between the mandibular notch, posterior ramus, anterior ramus, gonion, in both sides, in TPS graphs. On the other hand, a high level of deformations was observed in all landmarks that define the mandibular shape on rPR. The mandible dimorphism can be detected in the examination performed with geometric morphometric methods on cPR and rPR. While mandible shape differences according to gender are seen most in the ramus region in cPR, differences can be detected in all landmarks in rRP.

Carrier peptide interactions with liposome membranes induce reversible clustering by surface adsorption and shape deformation

The cell-penetrating peptide penetratin and its analogues shuffle and penetramax have been used as carrier peptides for oral delivery of therapeutic peptides such as insulin. Their mechanism of action for this purpose is not fully understood but is believed to depend on the interactions of the peptide with the cell membrane. In the present study, peptide-liposome interactions were investigated using advanced biophysical techniques including small-angle neutron scattering and fluorescence lifetime imaging microscopy. Liposomes were used as a model system for the cell membrane. All the investigated carrier peptides induced liposome clustering at a specific peptide/lipid ratio. However, distinctively different types of membrane interactions were observed, as the liposome clustering was irreversible for penetratin, but fully or partly reversible for shuffle and penetramax, respectively. All three peptides were found to adsorb to the surface of the lipid bilayers, while only shuffle and penetramax led to shape deformation of the liposomes. Importantly, the peptide interactions did not disrupt the liposomes under any of the investigated conditions, which is advantageous for their application in drug delivery. This detailed insight on peptide-membrane interactions is important for understanding the mechanism of peptide-based excipients and the influence of peptide sequence modifications.

Flexible and Red-Emissive Organic Single-Crystal Microresonator for Efficient Active Waveguides.

We fabricated a flexible and red-emissive microcrystal resonator for highly efficient optical waveguiding. The microfiber crystals of diketopyrrolopyrrole (DPP) used in this work possess a high photoluminescence (PL) quantum efficiency (ΦPL = 0.45) and exhibit a micromechanical deformation shape in the curved state. The crystals show optical fringes in their PL spectra, suggesting the existence of a naturally formed Fabry-Pérot crystal resonator owing to its flat crystal surface. The group refractive index (ng) and Rabi splitting energy (ℏΩ) indicating the coupling strength between excitons and resonator photons are large (ng = 3.7-6.0, ℏΩ = 1.38 eV), suggesting the strong confinement of waveguiding photons. Spatially resolved PL measurements revealed that the PL in a crystal fiber is efficiently waveguided, even in a curved crystal with a very small curvature radius of 11 μm. Strong photon confinement inside a crystal resonator is a plausible origin of efficient optical waveguiding.

Investigation on nonuniform current density and shape deformation affecting the magnetic field performance of a saddle-shaped no-insulation HTS cosine–theta dipole magnet

High magnetic fields are desirable for discovering new particles in particle accelerators. Dipole magnets using superconductors have played a key role in creating the required field intensity and uniformity. In contrast, high temperature superconductor (HTS) dipole magnets have recently been spotlit because of their ability to generate higher magnetic fields compared to their low temperature superconductor counterpart. Similar needs have emerged in other fields using magnets, and no-insulation (NI) technology is considered a feasible option to reach high magnetic fields by overcoming the disadvantages of HTS magnets. However, research has rarely been carried out on the utilization of NI HTS magnet technology for dipole magnets in high-field accelerators. Here we show the design, fabrication, and test results of an NI HTS dipole magnet with numerical analysis results. This paper aims to investigate the effect of nonuniform current density and undesirable shape deformation on the magnetic field distribution of a saddle-shaped NI HTS dipole magnet. The magnet is designed and constructed considering the ‘constant perimeter winding’ technique and tested in liquid nitrogen. The field mapping process is also performed along a designated mapping trajectory to obtain the magnetic field distribution. A T-A formulation-based simulation model, named the ‘sequential simulation model,’ is suggested to reproduce the measurements and employed considering the current distribution and shape deformation. As a result of quantitative analysis of the transverse direction measurements, the magnetic field error decreased by 0.02 percent point (pp) when the nonuniform current density is considered. It decreased by 0.13 pp when the shape deformation is considered. Moreover, the critical current calculated through an additional numerical analysis shows an error of up to 10%. In conclusion, the saddle-shaped NI HTS dipole magnet can produce a sufficient magnetic field level for particle accelerator research, even though the field distribution shows a uniformity of 0.37% within this study.