Efficient parallelization strategy for real-time FE simulations

This paper introduces an efficient and generic framework for finite-element simulations under an implicit time integration scheme. Being compatible with generic constitutive models, a fast matrix assembly method exploits the fact that system matrices are created in a deterministic way as long as the mesh topology remains constant. Using the sparsity pattern of the assembled system brings about significant optimizations on the assembly stage. As a result, developed techniques of GPU-based parallelization can be directly applied with the assembled system. Moreover, an asynchronous Cholesky precondition scheme is used to improve the convergence of the system solver. On this basis, a GPU-based Cholesky preconditioner is developed, significantly reducing the data transfer between the CPU/GPU during the solving stage. We evaluate the performance of our method with different mesh elements and hyperelastic models and compare it with typical approaches on the CPU and the GPU

Vers des performances en temps réel dans les simulations physiques à grande échelle

Les simulations physiques ont suscité une attention considérable dans le domaine médical, en particulier dans le domaine des chirurgies virtuelles. Une préoccupation actuelle de la recherche dans ce domaine est centrée sur l'obtention de comportements physiques réalistes dans les simulations en temps réel d'objets déformables. Cependant, cela présente un défi car les simulations doivent concilier les exigences contradictoires de précision et de temps de calcul rapide simultanément. Bien que la finesse de la discrétisation soit préférée pour capturer des informations de forme détaillées, elle conduit souvent à des systèmes plus importants au prix d'une augmentation des coûts de calcul. L'objectif principal de ce manuscrit est d'améliorer les performances de calcul afin de permettre des simulations en temps réel à grande échelle. Pour atteindre cet objectif, notre travail englobe plusieurs méthodes visant à relever les défis de la résolution du système numérique dans différents domaines problématiques.Physics-based simulations have garnered considerable attention in the medical field, particularly in the application of virtual surgeries. A current focus of research in this field is centered on achieving realistic physical behaviors in real-time simulations of deformable objects. However, this presents a challenge as simulations must fulfill the conflicting requirements of both accuracy and fast computation time simultaneously. While fine discretization is preferred for capturing detailed shape information, it often leads to larger systems with the cost of increased computational costs. The primary objective of this manuscript is to enhance computing performance to enable real-time simulations on a large scale. To address this objective, our work encompasses several methods aimed at overcoming challenges in numerical system resolution within various problem domains

Vers des performances en temps réel dans les simulations physiques à grande échelle

Physics-based simulations have garnered considerable attention in the medical field, particularly in the application of virtual surgeries. A current focus of research in this field is centered on achieving realistic physical behaviors in real-time simulations of deformable objects. However, this presents a challenge as simulations must fulfill the conflicting requirements of both accuracy and fast computation time simultaneously. While fine discretization is preferred for capturing detailed shape information, it often leads to larger systems with the cost of increased computational costs. The primary objective of this manuscript is to enhance computing performance to enable real-time simulations on a large scale. To address this objective, our work encompasses several methods aimed at overcoming challenges in numerical system resolution within various problem domains.Les simulations physiques ont suscité une attention considérable dans le domaine médical, en particulier dans le domaine des chirurgies virtuelles. Une préoccupation actuelle de la recherche dans ce domaine est centrée sur l'obtention de comportements physiques réalistes dans les simulations en temps réel d'objets déformables. Cependant, cela présente un défi car les simulations doivent concilier les exigences contradictoires de précision et de temps de calcul rapide simultanément. Bien que la finesse de la discrétisation soit préférée pour capturer des informations de forme détaillées, elle conduit souvent à des systèmes plus importants au prix d'une augmentation des coûts de calcul. L'objectif principal de ce manuscrit est d'améliorer les performances de calcul afin de permettre des simulations en temps réel à grande échelle. Pour atteindre cet objectif, notre travail englobe plusieurs méthodes visant à relever les défis de la résolution du système numérique dans différents domaines problématiques

EFFICIENT PARALLELIZATION STRATEGY FOR REAL-TIME FE SIMULATIONS

This paper introduces an efficient and generic framework for finite-element simulations under an implicit time integration scheme. Being compatible with generic constitutive models, a fast matrix assembly method exploits the fact that system matrices are created in a deterministic way as long as the mesh topology remains constant. Using the sparsity pattern of the assembled system brings about significant optimizations on the assembly stage. As a result, developed techniques of GPU-based parallelization can be directly applied with the assembled system. Moreover, an asynchronous Cholesky precondition scheme is used to improve the convergence of the system solver. On this basis, a GPU-based Cholesky preconditioner is developed, significantly reducing the data transfer between the CPU/GPU during the solving stage. We evaluate the performance of our method with different mesh elements and hyperelastic models and compare it with typical approaches on the CPU and the GPU

An efficient implicit constraint resolution scheme for interactive FE simulations

This paper presents a novel implicit scheme for the constraint resolution in real-time finite element simulations in the presence of contact and friction. Instead of using the standard motion correction scheme, we propose an iterative method where the constraint forces are corrected in Newton iterations. In this scheme, we are able to update the constraint directions recursively, providing more accurate contact and friction response. However, updating the constraint matrices leads to massive computation costs. To address the issue, we propose separating the constraint direction and geometrical mapping in the contact Jacobian matrix and reformulating the schur-complement of the system matrix. When combined with GPU-based parallelization, the reformulation provides a very efficient updating process for the constraint matrices in the recursive corrective motion scheme. Our method enables the possibility to handle the inconsistency of constraint directions at the beginning and the end of time steps. At the same time, the resolution process is kept as efficient as possible. We evaluate the performance of our fast-updating scheme in a contact simulation and compare it with the standard updating scheme

Real‐Time FE Simulation for Large‐Scale Problems Using Precondition‐Based Contact Resolution and Isolated DOFs Constraints

International audienceThis paper presents a fast method to compute large-scale problems in real-time finite element simulations in the presence of contact and friction. The approach uses a precondition-based contact resolution that performs a Cholesky decomposition at low frequency. On exploiting the sparsity in assembled matrices, we propose a reduced and parallel computation scheme to address the expensive computation of the Schur-complement arisen by detailed mesh and accurate contact response. An efficient GPU-based solver is developed to parallelise the computation, making it possible to provide real-time simulations in the presence of coupled constraints for contact and friction response. In addition, the pre-conditioner is updated at low frequency, implying reuse of the factorised system. To benefit a further speedup, we propose a strategy to share the resolution information between consecutive time steps. We evaluate the performance of our method in different contact applications and compare it with typical approaches on CPU and GPU

Efficient Needle Insertion Simulation using Hybrid Constraint Solver and Isolated DOFs

International audienceThis paper introduces a real-time compatible method to improve the location of constraints between a needle and tissues in the context of needle insertion simulation. This method is based on intersections between the Finite Element (FE) meshes of the needle and the tissues. It is coupled with the method of isolating mechanical DOFs and a hybrid solver (implying both direct and iterative resolutions) to respectively generate and solve the constraint problem while reducing the computation time

A Hybrid Cryptography Scheme for NILM Data Security

Using fine-grained data analysis, non-invasive load monitoring (NILM) can reveal the detail of electricity customers’ habits, which is helpful in the improvement of refined management and better user experience. However, the possibility of electricity customers’ privacy leak is also gradually increasing, and the security of NILM data has become a priority problem to be solved. To protect the privacy disclosure of NILM data, this paper analyzes the NILM privacy leak problems and ways in which information leak occurs faced by NILM data. On the basis of the comprehensive survey of cryptographic algorithms to choose the most appropriate data security method for NILM, a hybrid cryptography scheme was proposed to protect the data security. In the scheme, symmetric algorithm AES (Advanced Encryption Standard) was used to encrypt data for high efficiency, and asymmetric algorithm RSA (Rivest-Shamir-Adleman) was used to encrypt AES key for identity authentication. The classical algorithm HMAC-SHA1 (Hash Message Authentication Codes-Secure Hash Algorithm 1) was further developed to guarantee the integrity of data. By transplanting the algorithm into STM32 MCU (STMicroelectronics 32 bit Micro Controller Unit) for performance test and using Visual studio 2017 + QT tools to develop the test interface, one optimal operation mode was selected for the scheme. At the same time, the effectiveness of the scheme was verified, and the scheme computing cost depended on the efficiency of encryption and decryption, or signature and verification of the RSA algorithm