3D Solution Research Articles

Automated generation of 0D and 1D reduced-order models of patient-specific blood flow.

Three-dimensional (3D) cardiovascular fluid dynamics simulations typically require hours to days of computing time on a high-performance computing cluster. One-dimensional (1D) and lumped-parameter zero-dimensional (0D) models show great promise for accurately predicting blood bulk flow and pressure waveforms with only a fraction of the cost. They can also accelerate uncertainty quantification, optimization, and design parameterization studies. Despite several prior studies generating 1D and 0D models and comparing them to 3D solutions, these were typically limited to either 1D or 0D and a singular category of vascular anatomies. This work proposes a fully automated and openly available framework to generate and simulate 1D and 0D models from 3D patient-specific geometries, automatically detecting vessel junctions and stenosis segments. Our only input is the 3D geometry; we do not use any prior knowledge from 3D simulations. All computational tools presented in this work are implemented in the open-source software platform SimVascular. We demonstrate the reduced-order approximation quality against rigid-wall 3D solutions in a comprehensive comparison with N=72 publicly available models from various anatomies, vessel types, and disease conditions. Relative average approximation errors of flows and pressures typically ranged from 1% to 10% for both 1D and 0D models, measured at the outlets of terminal vessel branches. In general, 0D model errors were only slightly higher than 1D model errors despite requiring only a third of the 1D runtime. Automatically generated ROMs can significantly speed up model development and shift the computational load from high-performance machines to personal computers.

Efficient Numerical Simulation of Density‐Driven Flows: Application to the 2‐ and 3‐D Elder Problem

AbstractModeling density‐driven flow in porous media is challenging due to the nonlinear coupling between flow and transport equations, the large domains of interest and the wide range of time and space scales involved. Solving this type of problem numerically using a fixed mesh can be prohibitively expensive. Here, we apply a dynamic mesh optimization (DMO) technique along with a control‐volume‐finite element method to simulate density‐driven flows. DMO allows the mesh resolution and geometry to vary during a simulation to minimize an error metric for one or more solution fields of interest, refining where needed and coarsening elsewhere. We apply DMO to the Elder problem for several Rayleigh numbers. It is demonstrated that DMO accurately reproduces the unique two‐dimensional (2D) solutions for low Rayleigh number cases at significantly lower computational cost compared to an equivalent fixed mesh, with speedup of order ×16. For unstable, high Rayleigh number 2D cases, multiple steady‐state fingering solutions exist and are all captured by our approach with high accuracy and significantly reduced computational cost, with speedup of order ×6. Velocity‐dependent dispersion is shown to have a small impact on the 2D numerical solutions. The lower computational cost of simulations using DMO allows extension of the high Rayleigh number case to a three dimensional (3D) configuration. We demonstrate new 3D fingering patterns that have not been observed previously. Early time, transient 3D patterns represent combinations of the previously observed, steady‐state 2D solutions, but all evolve to a single, steady‐state finger in the late time limit.

Modeling of Multiple Fatigue Cracks for the Aircraft Wing Corner Box Based on Non-ordinary State-based Peridynamics

In the current research, we propose a novel non-ordinary state-based peridynamics (PD) fatigue model for multiple cracks’ initiation and growth under tension–tension fatigue load. In each loading cycle, the fatigue loading is redistributed throughout the peridynamic solid body, leading to progressive fatigue damage formation and expansion in an autonomous fashion. The proposed fatigue model parameters are first verified by a 3D numerical solution, and then, the novel model is used to depict the widespread fatigue damage evolution of the aircraft wing corner box. The modified constitutive damage model has been implemented into the peridynamic framework. Furthermore, the criteria and processes from multiple initiations to propagation are discussed in detail. It was found that the computational results obtained from the PD fatigue model were consistent with those from the test data. The angular errors of multiple cracks are within 2.66% and the number of cycles errors are within 15%. A comparison of test data and computational results indicates that the fatigue model can successfully capture multiple crack formations and propagation, and other behaviors of aluminum alloy material.

Automated Defect Recognition for Additive Manufactured Parts Using Machine Perception and Visual Saliency.

Metal additive manufacturing (AM) is known to produce internal defects that can impact performance. As the technology becomes more mainstream, there is a growing need to establish nondestructive inspection technologies that can assess and quantify build quality with high confidence. This article presents a complete, three-dimensional (3D) solution for automated defect recognition in AM parts using X-ray computed tomography (CT) scans. The algorithm uses a machine perception framework to automatically separate visually salient regions, that is, anomalous voxels, from the CT background. Compared with supervised approaches, the proposed concept relies solely on visual cues in 3D similar to those used by human operators in two-dimensional (2D) assuming no a priori information about defect appearance, size, and/or shape. To ingest any arbitrary part geometry, a binary mask is generated using statistical measures that separate lighter, material voxels from darker, background voxels. Therefore, no additional part or scan information, such as CAD files, STL models, or laser scan vector data, is needed. Visual saliency is established using multiscale, symmetric, and separable 3D convolution kernels. Separability of the convolution kernels is paramount when processing CT scans with potentially billions of voxels because it allows for parallel processing and thus faster execution of the convolution operation in single dimensions. Based on the CT scan resolution, kernel sizes may be adjusted to identify defects of different sizes. All adjacent anomalous voxels are subsequently merged to form defect clusters, which in turn reveals additional information regarding defect size, morphology, and orientation to the user, information that may be linked to mechanical properties, such as fatigue response. The algorithm was implemented in MATLAB™ using hardware acceleration, that is, graphics processing unit support, and tested on CT scans of AM components available at the Center for Innovative Materials Processing through Direct Digital Deposition (CIMP-3D) at Penn State's Applied Research Laboratory. Initial results show adequate processing times of just a few minutes and very low false-positive rates, especially when addressing highly salient and larger defects. All developed analytic tools can be simplified to accommodate 2D images.

Transient swelling of cylindrical hydrogels under coupled extension-torsion: Analytical and 3D FEM solutions

To design more accurate soft sensors and actuators, there is a significant requirement for the application of complicated deformation conditions. Coupled extension-torsion is a type of deformation which may be utilized in the property characterization of materials with complex behavior such as soft hydrogels. Hydrogels with coupled diffusion and large deformation behavior have intricate kinetics which should be studied in detail. In this work, a robust semi-analytical procedure is proposed to capture the transient behavior of cylindrical hydrogels in combined loading of extension and torsion in different conditions. Moreover, the whole problem with the same conditions is simulated in COMSOL-Multiphysics as a verification framework of the proposed semi-analytical procedure, where comparing the results shows a good agreement. The results demonstrate that the transient behavior of the cylindrical hydrogel under coupled extension-torsion is significantly dependent on the rate of the deformation and material properties. Besides, since the hydrogel undergoes a highly nonlinear swelling in this deformation regime, the simulations predict a complicated reaction force and moment. Visualizing the effect of different parameters engaged in the material shows the robust behavior of the proposed semi-analytical procedure, which can be employed in constitutive models’ calibration as well as in the design and optimization of hydrogels structures.

PCA Benchmark Analysis with ADVANTG3.0.1. and MCNP6.1.1b Codes

The Pool Critical Assembly Pressure Vessel (PCA) benchmark is a well known benchmark in the reactor shielding community which is described in the Shielding Integral Benchmark Archive and Database (SINBAD). It is based on the experiments performed at the PCA facility in the Oak Ridge National Laboratory (ORNL) and it can be used for the qualification of the pressure vessel fluence calculational methodology. The measured quantities to be compared against the calculated values are the equivalent fission fluxes at several experimental access tubes (A1 to A8) in front, behind, and inside the pressure-vessel wall simulator. This benchmark is particularly suitable to test the capabilities of the shielding calculational methodology and cross-section libraries to predict invessel flux gradients because only a few approximations are necessary in the overall analysis. This benchmark was analyzed using a modern hybrid stochastic-deterministic shielding methodology with ADVANTG3.0.1 and MCNP6.1.1b codes. ADVANTG3.0.1 is an automated tool for generating variance reduction (VR) parameters for Monte Carlo (MC) calculations with MCNP5v1.60 code (and higher versions). It is based on the multigroup, discrete ordinates solver Denovo, used for approximating the forward-adjoint transport fluxes to construct VR parameters for the final MC simulation. The VR parameters in form of the weight windows and the source biasing cards can be directly used with unmodified MCNP input. The underlining CADIS methodology in Denovo code was initially developed for biasing local MC results, such as point detector or a limited region detector. The FW-CADIS extension was developed for biasing MC results globally over a mesh tallies or multiple point/region detectors. Both CADIS and FW-CADIS are based on the concept of the neutron importance function, which is a solution of the adjoint Boltzmann transport equation. The equivalent fission fluxes calculated with MCNP are based on several highenergy threshold reactions from international dosimetry libraries IRDF-2002 and IRDFF-2014, distributed by the IAEA Nuclear Data Section. The obtained results show a good agreement with referenced PCA measurements. Visualization of the deterministic solution in 3D was done using the VisIt code from the Lawrence Livermore National Laboratory (LLNL).

Strategies of GNSS processing and measuring under various operational conditions

Purpose. GNSS technology is one of the key elements of maintenance of the mining works. Mostly, the GNSS observations in mining regions are accomplished under adverse surveying conditions. The presented paper is aimed at studying the problem of GNSS accuracy under various adverse operational conditions that may encounter during surveying works in deposit fields and downgrade the GNSS accuracy. Methodology. Despite the well-defined problem of GNSS accuracy, each year, new receiver models and software versions come into use, which in turn, needs a more profound analysis of their reliability, accuracy, and efficiency. This study provides relevant information about the static tests that were executed in the canopy, multipath, and open environments to assess the performance of the user segment from different manufacturers. The equipment of three manufactures was tested: Leica, Trimble, and Javad. The test results for two satellite systems, GPS and GLONASS, are presented. Findings. The obtained results can be generalized to the following outputs. Trimble performed the best on the canopy site in terms of position quality and fix solution. Javad had the best agreement for horizontal, height, and 3D solutions between dual and single frequency processing on the multipath site. On the open spot, Leicas horizontal solution between dual and single frequency processing was the most consistent. It is challenging to state which receiver performed better in the vegetation cover. Originality.The study aims to develop a general procedure to estimate the accuracy of different GNSS processing strategies under different environments. Practical value. The given research has a strong hands-on background insofar as the principal stress is made on field measurements. The research results can be employed to refine the GNSS surveying workflow for open-pit mines.

Assessment of refined higher order theories for the static and vibration analysis of laminated composite cylindrical shells

In the present study, a generalized shell theory is presented and applied for the analysis of laminated composite cylindrical shells. A theoretical unification of the several refined shell theories is presented. The principle of work done is employed to derive five differential equations corresponding to five unknowns involved in the present generalized shell theory. Five differential equations are solved by an analytical procedure suggested by the Navier. The numerical results for simply supported laminated composite cylindrical shells are presented and compared with 3D elasticity solutions. Displacements, stresses and fundamental frequencies are obtained for isotropic, orthotropic, 00/900 and 00/900/00 laminated cylindrical shells. The numerical results are obtained for h/a=0.1, a/b=1 and different values of R/a ratio. Displacements and stresses of laminated cylindrical shells are estimated under sinusoidal transverse load. In the case of free vibration analysis, first five natural frequencies are presented. It is observed that refined theories predicts displacements and stresses in close agreement with 3D elasticity solutions whereas the FST and the CST underpredict the displacements and stresses. It is also observed that the CST overestimates the natural frequencies due to neglect of shear deformation effect.

Trend analysis in the 1D solution of the inverse heat conduction problem by the sequential function specification technique

Inverse heat conduction problems are categorized by the solution technique or algorithm (Function Specification, Regularization, Laplace Transform, Conjugate Gradient, Mollification), by the solution method (Duhamel's Theorem, Difference Method Finite, Finite Element Method), and by the time domain (Stoltz Method, Sequential Method, and Complete Domain). In the direct approach, the unique solution of an effect due to a cause is obtained. From the cause-effect view, inverse problems are characterized by not meeting the existing criteria and the uniqueness of determining the cause when analyzing an effect. However, this has promoted the implementation of robust methods to optimize the stability of a solution. In this work, the study system consists of a long solid cylinder at an elevated temperature that is cooled. The implemented methodology allowed the creation of data trends through linear extrapolation to improve estimation accuracy for abrupt changes in the function (boundary condition). The results show an acceptable increase in punctual precision in the estimation, and it is a consequence of the solution that the calculated thermal histories already contain an implicit degree of error.

Fast 2.5D and 3D inversion of transient electromagnetic surveys using the octree-based finite-element method

Two efficient implementations of 3D and 2.5D modeling and inversion are presented to be applicable to large-scale transient electromagnetic (TEM) method explorations. The key novel features are (1) forward response and Jacobian calculations are implemented using the octree-based finite-element method, (2) a mirror approach is used to build a 2.5D inversion scheme for further efficiency, and (3) a flexible link between the forward mesh and inversion model is applied on 3D and 2.5D schemes based on the voxel formulation. We compare the performance of the new implementations with 3D modeling using tetrahedral meshes, with respect to speed and memory requirements. The 3D octree algorithm requires less than 1/3 of the computational time compared with a 3D tetrahedral scheme for equivalent accuracy. The 2.5D octree algorithm further speeds up the process by reducing the computational time by another factor of two. The inversion uses the Levenberg-Marquart approach minimizing the least-squares criterion of the objective function. We determine the utility of our inversion approach on a synthetic example and a field example. In the synthetic example, the 3D octree inversion result finds superior resolution of a 3D anomaly compared with a 1D result, whereas the 2.5D inversion result is, expectedly, between the 1D and 3D results, but with favorable computational expenses compared with the full 3D solution. The field data set contains 200 soundings, and we perform a 3D inversion on the full survey. A 24-sounding section is then selected for the 2.5D inversion. The 2.5D inversion result finds resistivity features similar to the 3D inversion result at the selected profile. Hence, we conclude that the presented implementations are capable of handling relatively large TEM surveys on modern computational platforms. This could be smaller subsets of production-size surveys where 2D and 3D effects are pronounced.

Intensifying the spatial resolution of 3D thermal models from aerial imagery using deep learning-based image super-resolution

Nowadays, 3D thermal models can play an important role in buildings' energy management while acquiring multisource data to generate a high-resolution 3D thermal model. Consequently, in this article, a method for intensifying 3D thermal model using deep learning-based image super-resolution is presented. In the proposed method, first, the enhanced deep residual super-resolution (EDSR) deep network is re-trained based on thermal aerial images. Second, the resolution of low-resolution thermal images is enhanced using the newly trained network. Finally, the state-of-the-art structures from motion (SfM), semi global matching (SGM) and space intersection are utilized to generate intensified 3D thermal model from the resolution enhanced thermal images. Spatial evaluations indicate a 5% increase in edge-based image fusion metric (EFM) for the intensified 3D model. Besides, the evaluations show that the modulation transfer function (MTF) curves of the intensified 3D thermal model are closer to a reference model against the original 3D thermal model. Highlights A 3D thermal model intensification solution using EDSR is proposed which is independent of hardware techniques and multisource data. Considering the importance of edge sharpness in the intensified 3D thermal model, the quality of edges is assessed using MTF curves and the EFM metric. In comparison to the original 3D thermal model, the MTF curves of the intensified 3D thermal model are closer to the MTF curve of the high-resolution 3D model. The EFM metric shows higher values for MTF curves of the intensified 3D thermal model against MTF curves of the original 3D thermal model.

Optical soliton analysis to a family of 3D WBBM equations with conformable derivative via a dynamical approach

The prime goal of this study is to investigate the soliton dynamics to the family of 3D fractional Wazwaz–Benjamin–Bona–Mahony​ (WBBM) equations in the absence of self-phase modulation by employing the advanced exp−ϕψ-expansion method. Our mentioned technique is a superior development of the generalized exp−ϕψ-expansion method. By employing the advanced exp−ϕψ-expansion method, optical soliton, singular optical soliton, dark optical soliton, combined optical soliton solutions are constructed to our mentioned family of 3D fractional WBBM equations, whereas trigonometric, hyperbolic, and rational function solutions are also obtained. Moreover, three-dimensional surface plots, contour plots, and two-dimensional plots are presented by the obtained solutions’ dynamical characteristics. All the plots of each solution are shown separately for real and imaginary parts. All the attained solutions have been proved by the computational software Mathematica.

3D anisotropic TEM modeling with loop source using model reduction method

Abstract For model reduction techniques, there have been relatively few studies performed regarding the forward modeling of anisotropic media in comparison to transient electromagnetic (TEM) forward modeling of isotropic media. The transient electromagnetic method (TEM) responses after the current has been turned off can be represented as a homogeneous ordinary differential equation (ODE) with an initial value, and the ODE can be solved using a matrix exponential function. However, the order of the matrix exponential function is large and solving it directly is challenging, thus this study employs the Shift-and-Invert (SAI-Krylov) subspace algorithm. The SAI-Krylov subspace technique is classified as a single-pole approach compared to the multi-pole rational Krylov subspace approach. It only takes one LU factorization of the coefficient matrix, along with hundreds of backward substitutions. The research in this paper shows that the anisotropic medium has little effect on the optimal shift ${\gamma _{opt}}$ and subspace order m. Furthermore, as compared to the mimetic finite volume method (SAI-MFV) of the SAI-Krylov subspace technique, the method proposed in this paper (SAI-FEM) can further improve the computing efficiency by roughly 13%. In contrast to the standard implicit time step iterative technique, the SAI-FEM method does not require discretization in time, and the TEM response at any moment within the off-time period can be easily computed. Next, the accuracy of the SAI-FEM algorithm was verified by 1D solutions for an anisotropic layer model and a 3D anisotropic model. Finally, the electromagnetic characteristics of the anisotropic anomalous body of the center loop device and separated device of the airborne transient electromagnetic method were analyzed, and it was found that horizontal conductivity has a considerable influence on the TEM response of the anisotropic medium.

Closed-form solutions for collapse mechanisms of tunnel crown in saturated non-uniform rock surrounds

The crown stability of a deep-buried metro tunnel or station is evaluated by means of a kinematic analysis procedure, with considerations of non-uniform rock surrounds and pore water effects. Non-uniform rock strata are discretized to several layers with finite thickness, with varying rock parameters assigned to different layers and constant parameters within each layer. Pore water effect is considered as an external loading acting on rock mass and boundaries. Employing the nonlinear Hoek-Brown criterion, a preliminary study is presented to analyse tunnel crown stability in a uniform rock medium, in the realm of upper bound theory. After having obtained general solutions of 2D and 3D collapse mechanisms, non-uniformity of rock masses is considered and investigated in crown stability analyses. 2D and 3D closed-form solution are formulated based on variational principle and work rate balance equation. Apart from the collapse shape and dimension, the weight of collapsing block is calculated, which gives a quick estimate of the average overburden pressure and hence guides the design of tunnel lining. Some examples related to circular and rectangular (square) tunnels are provided to offer insights of the implication of influential factors on the crown stability of a tunnel deeply excavated in saturated non-uniform rock strata.

Fabrication of a zirconia/calcium silicate composite scaffold based on digital light processing

Zirconia (ZrO2) and calcium silicate (CS) are widely used in bone repair. Zirconia has excellent mechanical properties, while calcium silicate has exceptional biological activity. A porous ZrO2/CS composite ceramic scaffold was formed by digital light processing (DLP) technology in this study. The microstructure analysis demonstrated that CS was embedded between ZrO2 particles. Mechanical tests showed that interconnected CS particles could improve mechanical properties, while discrete CS particles led to a decrease in that. Cell experiments showed that adding CS to ZrO2 had a positive effect on cell proliferation and differentiation. In vitro degradation test showed that the weight loss of scaffolds in four weeks increased form −0.63%–1.42% with the increase of CS content. Moreover, the degradation of scaffold promoted the deposition of apatite, which was beneficial to the integration of the scaffold with living bone. In conclusion, the ZrO2/CS composite scaffold had better biocompatibility compared with the ZrO2 scaffold, which showed a potential solution for 3D printing bone repair scaffolds.

Global spectral analysis of the Lax–Wendroff-central difference scheme applied to Convection–Diffusion equation

In this work, the Global Spectral Analysis (GSA) is applied to the convective Lax–Wendroff based discretization of linear convection–diffusion problem in both 1D and 2D. Contrary to standard numerical analysis approaches, two important physical processes (convection and diffusion) are treated together, thus making GSA a function of multiple non-dimensional numerical parameters, namely, the non-dimensional wavenumber (kh), the Courant–Friedrich–Lewy number (Nc) and the Peclet number (Pe). All the three quantities impact the stability of the numerical scheme by affecting both numerical amplification factor as well as numerical diffusion. Likewise, numerical phase speed and numerical group velocity all become expressions of all three non-dimensional parameters. Leveraging the GSA, an accurate map (property charts) of acceptable range of parameter space is evidenced to obtain the spatio-temporal numerical solution that is stable as well as Dispersion Relation Preserving (DRP). The numerical property charts are shown to be useful to calibrate numerical solutions of both 1D and the 2D convection–diffusion equations on uniform meshes. Finally, as demonstrated while solving the Navier–Stokes equation for a Taylor–Green vortex problem, property charts allow to explain numerical behaviors often observed with real complex flow problems.

A new electro-mechanical finite formulation for functionally graded graphene reinforced composite laminated thick plates with piezoelectric actuator

Graphene is regarded as one of the most attractive reinforcements for composite materials attributing to the extraordinary physical characteristics. However, existing models in the literatures might meet severe challenges for the interlaminar stress prediction of functionally graded graphene reinforced composite (FG-GRC) laminated thick plate integrated with piezoelectric fiber reinforced composite (PFRC) actuator under electro-mechanical loadings. If transverse shear deformations cannot be described accurately, the mechanical performance of FG-GRC laminated plate with PFRC actuator will be significantly impacted by the electro-mechanical coupling effect and the sudden change of material characteristics at the interfaces. Thereby, a new electro-mechanical coupled plate model with only seven independent displacement variables is to be proposed in this paper. Employing the Reissner mixed variational theorem (RMVT), the precision of the transverse shear stresses considering the electro-mechanical coupling effect can be improved. Moreover, the second-order derivatives of in-plane displacement parameters have been removed from the transverse shear stress components, which can greatly simplify the finite element formulation. Thus, based on the proposed electro-mechanical coupled plate model, a simple C0-type finite element formulation is developed for interlaminar shear stress analysis of FG-GRC laminated thick plate with a PFRC actuator. The 3D elasticity solutions and the results obtained from other models are used to assess the performance of the proposed finite element formulation. Additionally, comprehensive parametric studies are achieved for the influences of graphene volume fraction, distribution pattern, electro-mechanical loading, boundary conditions, lamination scheme and geometrical parameters of the plate on the deformations and stresses of the FG-GRC laminated plate with a PFRC actuator.

Three-Dimensional Theoretical Model for Soil Arching with Inclined Slip Surfaces

Terzaghi proposed two-dimensional (2D) arching theory through trapdoor tests based on the assumption of a vertical slip surfaces. However, the original 2D assumption is different from a real three-dimensional (3D) excavation condition and actual slip surfaces caused by the downward movement of a trapdoor are inclined surfaces. Therefore, a 3D theoretical model was proposed in this study considering inclined slip surfaces. Horizontal thin-layer differential element method was used to obtain the loosening soil pressure. Using the 3D theoretical model, the effects of the buried depth ratio of loose area, length of loose area, soil parameters, and lateral earth pressure coefficient were investigated. The loosening earth pressure was highly affected by inclination angle of slip surface, buried depth ratio and length of loose area. Neglecting the inclined slip surface will underestimate the value of the loosening earth pressure, which will lead to the insecurity of the design. Loosening earth pressure calculated by this study was also compared with trapdoor tests. Results from this study was in good agreement with the experimental results. Compared with the traditional 2D solution, results from this study can more accurately analyze the soil arching effect in 3D excavation cases.

The localized method of fundamental solutions for 2D and 3D inhomogeneous problems

In this paper, the newly-developed localized method of fundamental solutions (LMFS) is extended to analyze multi-dimensional boundary value problems governed by inhomogeneous partial differential equations (PDEs). The LMFS can acquire highly accurate numerical results for the homogeneous PDEs with an incredible improvement of the computational speed. However, the LMFS cannot be directly used for inhomogeneous PDEs. Traditional two-steps scheme has difficulties in finding the particular solutions, and will lead to a loss of the accuracy and efficiency. In this paper, the recursive composite multiple reciprocity method (RC-MRM) is adopted to re-formulate the inhomogeneous PDEs to higher-order homogeneous PDEs with additional boundary conditions, which can be solved by the LMFS efficiently and accurately. The proposed combination of the RC-MRM and the LMFS can analyze inhomogeneous governing equation directly and avoid troublesome caused by the two-steps schemes. The details of the numerical discretization of the RC-MRM and the LMFS are elaborated. Some numerical examples are provided to demonstrate the accuracy and efficiency of the proposed scheme. Furthermore, some key factors of the LMFS are systematically investigated to show the merits of the proposed meshless scheme.

Self-stabilizing spanner topology control solutions in wireless ad hoc networks

Large-scale, self-organizing wireless ad hoc network deployments are being driven by recent developments of the Internet of Things (IoT) to collect information from a vast area or harsh environment efficiently. How to ensure fast routing in sparse topology and after node failure how to ensure that the network keeps topology properties are challenging problems. In this paper, we propose a Self-stabilizing dIrected t-Spanner for Autonomous nodes problem (SISA) and give intuitive solutions in both 2D and 3D space. In the topology construction phase, sparse directed t-spanner topologies, without substantially degrading the path connecting any pair of nodes in the original network, are constructed with a minimum number of messages. In the topology maintenance phase, the self-stabilizing algorithms run in the background to update locally for keeping t-spanner property when some nodes fail. In particular, our solutions have not any central daemon and are completely distributed. Our experimental results demonstrate the effectiveness and efficiency of our proposed solutions.