Complex Topology Research Articles

Real-time soft body dissection simulation with parallelized graph-based shape matching on GPU

Background and ObjectiveInteractive soft tissue dissection has been a fundamental procedure in virtual surgery systems. Existing cutting algorithms involve complex topology changes of simulation meshes, which can increase simulation overhead and produce visual artifacts. In this paper, we proposed a novel graph-based shape-matching method that allows for real-time, flexible, progressive, and discontinuous cuts on soft tissue. MethodsWe employed shape-matching constraints within the position-based dynamics (PBD) framework, a widely adopted approach for real-time simulation applications. The soft tissue was effectively modeled using overlapping clusters, each governed by shape-matching constraints. The dissection process was bifurcated into two distinct stages. In the first stage, the surgical scalpel presses the surface of the soft tissue. The soft tissue is cut apart when the surface pressure exceeds a threshold, entering the second stage. To address the discrepancy between the visual mesh and the simulation model during cluster separation, we developed an Aggregate Finding Connected Components (AFCC) algorithm, optimized for GPU computation and integrated with a background grid. This approach also avoids ghost forces and fragmentation artifacts. To control the increase in the number of clusters, we also propose a merging strategy that can run in parallel. ResultsOur simulation outcomes demonstrated that the AFCC dissection algorithm effectively manages cluster separation and expansion with robustness. There were no ghost forces between the cutting surface and unrealistic fragments. Our simulation capability extended to supporting intricate and discontinuous cutting routes. Our dissection simulation maintained real-time performance even with over 100,000 particles constituting the soft tissue. ConclusionsOur real-time and robust surgical dissection simulation technique enables the performance of complex cuts in various surgical scenarios, demonstrating its potential in virtual surgery applications.

The Performance Enhancement of a Vehicle Suspension System Employing an Electromagnetic Inerter

As a newly conceived vibration isolation element, an inerter can be implemented in different forms, and it is easily introduced in different vibration isolation scenarios. This paper focuses on a novel inerter device called an electromagnetic inerter (EMI), which combines a linear generator with a fluid inerter. Firstly, the structure and the working principle of the EMI is stated. Then, the parameter sensitivity of the fluid inerter is analyzed, and two parameters that have great influence on the inertance coefficient are obtained. Subsequently, the influence of the change of the external circuit on the output characteristics of the device is also discussed. This proves that the introduction of external circuits can simplify complex mechanical topologies. Finally, the topological structures of vehicle suspension are changed in the form of an EMI (including external circuit), and the dynamic performance of these structures in the typical vibration isolation system of a vehicle’s suspension is obtained. It is found that an L4 layout should be considered as the best suspension structure. Compared with traditional passive suspension, it not only ensures that its handling stability is not weakened, but also reduces the root mean square value of body acceleration and the peak of suspension work space by 4.56% and 11.62%, respectively.

Collective Synthesis of Highly Oxygenated (Furano)germacranolides Derived from Elephantopus mollis and Elephantopus tomentosus.

Germacranolides, secondary metabolites produced by plants, have garnered academic and industrial interest due to their diverse and complex topology as well as a wide array of pharmacological activities. Molephantin, a highly oxygenated germacranolide isolated from medicinal plants, Elephantopus mollis and Elephantopus tomentosus, has exhibited antitumor, inflammatory, and leishmanicidal activities. Its chemical structure is based on a highly strained ten-membered macrocyclic backbone with an (E,Z)-dienone moiety, which is fused with an α-methylene-γ-butyrolactone and adorned with four successive stereogenic centers. Herein, we report the first synthesis of molephantin in 12 steps starting from readily available building blocks. The synthesis features the highly diastereoselective intermolecular Barbier allylation of the β,γ-unsaturated aldehyde with optically active 3-bromomethyl-5H-furan-2-one intermediate and ensuing Nozaki-Hiyama-Kishi (NHK) macrocyclization for the construction of the highly oxygenated ten-membered macrocyclic framework. This synthetic route enabled access to another germacranolide congener, tomenphantopin F. Furthermore, cycloisomerization of molephantin into 2-deethoxy-2β-hydroxyphantomolin could be facilitated by irradiation with ultraviolet A light (λmax=370 nm), which opened a versatile and concise access to the related furanogermacranolides such as EM-2, phantomolin, 2-O-demethyltomenphantopin C, and tomenphantopin C.

Collective Synthesis of Highly Oxygenated (Furano)germacranolides Derived from Elephantopus mollis and Elephantopus tomentosus

AbstractGermacranolides, secondary metabolites produced by plants, have garnered academic and industrial interest due to their diverse and complex topology as well as a wide array of pharmacological activities. Molephantin, a highly oxygenated germacranolide isolated from medicinal plants, Elephantopus mollis and Elephantopus tomentosus, has exhibited antitumor, inflammatory, and leishmanicidal activities. Its chemical structure is based on a highly strained ten‐membered macrocyclic backbone with an (E,Z)‐dienone moiety, which is fused with an α‐methylene‐γ‐butyrolactone and adorned with four successive stereogenic centers. Herein, we report the first synthesis of molephantin in 12 steps starting from readily available building blocks. The synthesis features the highly diastereoselective intermolecular Barbier allylation of the β,γ‐unsaturated aldehyde with optically active 3‐bromomethyl‐5H‐furan‐2‐one intermediate and ensuing Nozaki–Hiyama–Kishi (NHK) macrocyclization for the construction of the highly oxygenated ten‐membered macrocyclic framework. This synthetic route enabled access to another germacranolide congener, tomenphantopin F. Furthermore, cycloisomerization of molephantin into 2‐deethoxy‐2β‐hydroxyphantomolin could be facilitated by irradiation with ultraviolet A light (λmax=370 nm), which opened a versatile and concise access to the related furanogermacranolides such as EM‐2, phantomolin, 2‐O‐demethyltomenphantopin C, and tomenphantopin C.

Electromagnetic deformation of a high-precision radio navigation field consumers of the basins of the inland waterways of Russia

The basins of the inland waterways of the Russian Federation are characterized by a variety of specific navigation features, the destructive effects of which significantly affect the parameters of the purpose of radio navigation systems. Therefore, the task arises to develop a model and estimate the electromagnetic deformation of the high-precision radio navigation field in the basins of the inland waterways of Russia caused by their navigational features. The study and identification of the general navigational features of the basins of the inland waterways of Russia and the assessment of the degree of influence of their destabilizing factors on the quality indicators of the high-precision radio navigation field. New navigation features have been identified in the basins of the inland waterways of Russia, the destructive factors of which deform the high-precision radio navigation field and reduce the quality of transmission of differential corrections. The results obtained confirm a decrease in the accuracy of positioning unmanned vessels in sections of the waterway with a complex terrain topology and electromagnetic environment. At the same time, the positioning accuracy in river basins may deteriorate in local areas from 1.6 times (from 6.8 m to 28.7 m) to 4.3 times (from 27.3 m to 117 m), depending on the electro-magnetic situation and the value of the geometry coefficient. A decrease in the quality of differential correction transmission will be manifested at the boundaries of service areas and range from 1 dB in sparsely populated areas and up to 30 dB in industrial zones. These factors will reduce the safety of navigation, so they must be taken into account when operating ships and designing functional additions to the global nav. The results obtained in the work can be used in the formation and optimization of the topology of control and correction stations of differential additions to the global navigation satellite system and to meet the requirements for the accuracy of positioning of mobile objects in difficult physical and geographical conditions of the terrain and electromagnetic environment.

Membrane fission via transmembrane contact

Division of intracellular organelles often correlates with additional membrane wrapping, e.g., by the endoplasmic reticulum or the outer mitochondrial membrane. Such wrapping plays a vital role in proteome and lipidome organization. However, how an extra membrane impacts the mechanics of the division has not been investigated. Here we combine fluorescence and cryo-electron microscopy experiments with self-consistent field theory to explore the stress-induced instabilities imposed by membrane wrapping in a simple double-membrane tubular system. We find that, at physiologically relevant conditions, the outer membrane facilitates an alternative pathway for the inner-tube fission through the formation of a transient contact (hemi-fusion) between both membranes. A detailed molecular theory of the fission pathways in the double membrane system reveals the topological complexity of the process, resulting both in leaky and leakless intermediates, with energies and topologies predicting physiological events.

Universal properties of branched copolymers in dilute solutions

We analyze the universal conformational properties of complex copolymer macromolecules, based on two topologies: the rosette structure containing fc linear branches and fr closed loops grafted to the central core, and the symmetric pom-pom structure, consisting of a backbone linear chain terminated by two branching points with functionalities f. We assume that the constituent strands (branches) of these structures can be of two different chemical species a and b. Depending on the solvent conditions, the inter- or intrachain interactions of some links may vanish, which corresponds to Θ-state of the corresponding polymer species. Applying both the analytical approach within the frames of direct polymer renormalization and numerical simulations based on the lattice model of polymer, we evaluated the set of parameters characterizing the size properties of constituent parts of two complex topologies and estimated quantitatively the impact of interactions between constituent parts on these size characteristics.

DeepBranchTracer: A Generally-Applicable Approach to Curvilinear Structure Reconstruction Using Multi-Feature Learning

Curvilinear structures, which include line-like continuous objects, are fundamental geometrical elements in image-based applications. Reconstructing these structures from images constitutes a pivotal research area in computer vision. However, the complex topology and ambiguous image evidence render this process a challenging task. In this paper, we introduce DeepBranchTracer, a novel method that learns both external image features and internal geometric characteristics to reconstruct curvilinear structures. Firstly, we formulate the curvilinear structures extraction as a geometric attribute estimation problem. Then, a curvilinear structure feature learning network is designed to extract essential branch attributes, including the image features of centerline and boundary, and the geometric features of direction and radius. Finally, utilizing a multi-feature fusion tracing strategy, our model iteratively traces the entire branch by integrating the extracted image and geometric features. We extensively evaluated our model on both 2D and 3D datasets, demonstrating its superior performance over existing segmentation and reconstruction methods in terms of accuracy and continuity.

A Hybrid Global-Local Perception Network for Lane Detection

Lane detection is a critical task in autonomous driving, which requires accurately predicting the complex topology of lanes in various scenarios. While previous methods of lane detection have shown success, challenges still exist, especially in scenarios where lane markings are absent. In this paper, we analyze the role of global and local features in accurately detecting lanes and propose a Hybrid Global-Local Perception Network (HGLNet) to leverage them. Global and local features play distinct roles in lane detection by respectively aiding in the detection of lane instances and the localization of corresponding lanes. HGLNet extracts global semantic context by utilizing a global extraction head that aggregates information about adaptive sampling points around lanes, achieving an optimal trade-off between performance and efficiency. Moreover, we introduce a Multi-hierarchy feature aggregator (MFA) to capture feature hierarchies in both regional and local ranges, elevating the representation of local features. The proposed Hybrid architecture can simultaneously focus on global and local features at different depth levels and efficiently integrate them to sense the global presence of lanes and accurately regress their locations. Experimental results demonstrate that our proposed method improves detection accuracy in various challenging scenarios, outperforming the state-of-the-art lane detection methods.

Centres of rigidity in multi-storey asymmetric diaphragm systems for eigenmodal vibrations

In this paper a general methodology is proposed for calculating the centres of rigidity of multi-storey asymmetric buildings subjected to eigenmodal vibrations with possible modal damping. The methodology is applicable to any building with horizontal diaphragms, even to those with complex topology, possible coupling of diaphragms and existence of additional masses out of diaphragms, assuming linearly elastic behaviour. The methodology is presented in a simple formulation, using only the stiffness resisting diaphragm forces during these vibrations. The methodology uses the results of two eigenmodes obtained by eigenmodal analysis, which can be carried out by a variety of standard programs for dynamic analysis of structures, along with a small post-processing effort that can be easily programmed in a worksheet. A numerical example presents the individual steps of the proposed methodology, while two additional numerical examples demonstrate it's simplicity and efficiency. It is shown that the centres of rigidity lie on a fixed position in each diaphragm for each proper pair of eigenmodal vibrations, irrespective of the existence of modal damping, and therefore they can be included in the basic dynamic characteristics of the building.

Unraveling the Influence of Topology and Spatial Confinement on Equilibrium and Relaxation Properties of Interlocked Ring Polymers.

We use Langevin dynamics simulations to study linked ring polymers in channel confinement. We address the in- and out-of-equilibrium behavior of the systems for varying degrees of confinement and increasing topological and geometrical complexity of the interlocking. The main findings are three. First, metric observables of different link topologies collapse onto the same master curve when plotted against the crossing number, revealing a universal response to confinement. Second, the relaxation process from initially stretched states is faster for more complex links. We ascribe these properties to the interplay of several effects, including the dependence of topological friction on the link complexity. Finally, we show that transient forms of geometrical entanglement purposely added to the initial stressed state can leave distinctive signatures in force-spectroscopy curves. The insight provided by the findings could be leveraged in single-molecule nanochannel experiments to identify geometric entanglement within topologically linked rings.

Topological Complex Charge Conservation in Nontrivial Z2 × Z2 Domain Walls.

Localized topological modes such as solitons, Majorana Fermions, and skyrmions are attracting great interest as robust information carriers for future devices. Here, a novel conserved quantity for topological domain wall networks of a Z2 ×Z2order generated with spin-polarized current in Sr2VO3FeAs is discovered. Domain walls are mobilized by the scanning tunneling current, which also observes in atomic scale active dynamics of domain wall vertices including merge, bifurcation, pair creation, and annihilation. Within this dynamics, the product of the topological complex charges defined for domain wall vertices is conserved with a novel boundary-charge correspondence rule. These results may open an avenue toward topological electronics based on domain wall vertices in generic Z2 ×Z2systems.

Intelligent driving model considering vehicular dynamics and heterogeneous road environments

ABSTRACT Understanding vehicles’ movement in complex environments becomes cruical with the fast development of connected automated vehicles (CAVs). Current microscopic traffic flow models lack consideration for vehicle dynamics and complex road topologies. This study develops a model addressing these issues, retrieving vehicles’ maneuvers and predicting vehicles’ two-dimensional motion. It introduces a two-dimensional intelligent driving model utilizing steering angle and acceleration as control inputs. Intricate road topologies are represented with potential fields and a virtual boundary to capture the heterogeneous environment’s complexity. A driving potential field model is also developed for off-ramp areas. Model parameters are optimized with the dynamic time warping (DTW) and particle swarm optimization (PSO) algorithm. Furthermore, model predictive control (MPC) enhances the realism of the model’s output. Field validation results demonstrate that the proposed models can accurately describe vehicles’ two-dimensional movement in intricate environments, offering valuable support for research on heterogeneous traffic flows for CAVs and CVs.

A nitric oxide-triggered hydrolysis reaction to construct controlled self-assemblies with complex topologies

A nitric oxide-triggered hydrolysis reaction to construct controlled self-assemblies with complex topologies

Accurate Simulation-Based Predictions of Assembly Force and Deformation for Warped Thin-Walled Components Characterized by Geometric and Topological Complexities

Accurate Simulation-Based Predictions of Assembly Force and Deformation for Warped Thin-Walled Components Characterized by Geometric and Topological Complexities

Efficient Structure Transformation Based on Sensitivity-Oriented Structure Adjustment for Inverse-Designed Devices

Inverse-designed devices with thousands of degrees of freedom could achieve high performance in compact footprints, but typically have complex structure topologies that contain many irregular and tiny features and sharp corners, which tend to lead to a poor robustness to fabrication errors. In order to effectively transform the structure of inverse-designed nanophotonic devices into simple structure topologies that have high robustness to fabrication errors without sacrificing device performance, in this paper, we propose a structure adjustment method that innovatively adjusts the structures of inverse-designed devices by introducing their structural sensitivity to the optical performance, extracting the device substructures with high sensitivity and eliminating those with low sensitivity, and, finally, transforming the device structures into simple structure topologies with high robustness and better performance. Two devices (90° crossing and T-junction) were designed and fabrication tolerance simulation was conducted to verify the method. The results show that the devices designed using the proposed method achieved better performance and were more robust to under/over-etched errors.

Raster approach to modelling the failure of arbitrarily inclined interfaces with structured meshes

This paper presents an approach to evaluate the failure of arbitrarily inclined interfaces using FE models with structured spatial discretization, providing accurate prediction of crack propagation along paths known a priori that are not constrained to the element boundaries. The combination of algorithms for the generation of structured discretization of representative polycrystalline microstructures with novel cohesive element formulations allow modelling the failure of complex topologies along rasterised boundaries, with noticeably higher computational efficiency and comparable accuracy. Two formulations of raster cohesive elements are presented, adopting either elastic-brittle or Tvergaard–Hutchinson traction separation laws. The formulations proposed are first validated comparing the failure of the interface within bi-crystal structures discretised using hexahedral elements either within a structured mesh (i.e. with rasterised boundaries) or an unstructured mesh (i.e. with planar boundary). Subsequently, the effectiveness of the formulations is demonstrated comparing the inter-granular crack propagation within complex polycrystalline microstructures. The behaviour of the novel cohesive element formulation in structured meshes consisting of regular hexahedral elements is in excellent agreement with the deformation and failure of classic cohesive element formulations placed along the planar boundaries of unstructured meshes consisting of tetrahedral elements. The higher computational cost of the raster cohesive elements is more than compensated by the increase in computational efficiency of structured meshes when compared to unstructured meshes, leading to a reduction of the simulation time of up to over 200 times for the simulations presented in the paper, thus allowing the simulation of large domains.

Lattice concrete: 3D printed periodic cellular structures through selective cement hydration

3D printing of concrete allows fabrication of complex shapes and structures. Among various 3D printing approaches, the particle bed 3D printing technique has gained attention in recent years, especially for its ability to generate complex topologies that are otherwise impossible to make using cement-paste extrusion-based techniques. In this work, we present our trials on 3D printing cellular lattice concrete structures using a powder bed technique by employing selective cement hydration. Specifically, we print two-types of cellular concrete blocks (i) with interconnected spherical voids and (ii) with gyroid structures, each block with uniform edge lengths of 15 cm. We use Ordinary Portland Cement, fine-grained sand, and normal water, without the use of any admixtures or additives. The printing technology used was custom-made and is quite simple and inexpensive involving a syringe based water jetting on to a powder bed of cement and sand mixture. We discuss the quality of the printed specimens obtained as well as their strength characteristics. An inadvertent observation was made, where a compressive strength gain by a factor of more than 2 was obtained in specimens that were exposed to open atmosphere for a long duration after a 28 day curing period compared to those that were tested immediately after curing. The current study demonstrates the feasibility of fabricating cellular lattice concrete structures that can potentially be useful as programmable metamaterials for civil engineering applications.

Searching by Topological Complexity: Lightweight Neural Architecture Search for Coal and Gangue Classification

Searching by Topological Complexity: Lightweight Neural Architecture Search for Coal and Gangue Classification

Comparative Analysis of PCC and ECMP Methods in Load Balancing Using GNS3 Simulator

Judging from daily activities, human beings heavily rely on the internet for communication purposes. and exchange information using either social media applications or browsers, vonsistently fast internet speeds are incredibly beneficial for performing tasks and activities, particularly for students and professionals. A sluggish internet connection can be frustrating and may lead to interruptions in online activities and tasks if it persists. Hence, this study examines a comparative evaluation of two approaches, Per Connection Classifier (PCC) and Equal Cost Multi-Path (ECMP) in Load Balancing through GNS3 simulation. Load balancing, as a method for evenly distributing traffic loads, and failover, as a backup mechanism when the main connection experiences problems. GNS3 is a graphical network simulator program that can transmit more complex network topologies compared to other simulators, for example Cisco Packet Tracer. The primary aim of this study is to comprehend how efficiently both techniques distribute traffic loads, maintaining smooth internet access, and increasing reliability. The PCC method produces better throughput, delay and jitter compared to the ECMP method, even though it has slightly different values for each QoS parameter. In testing traffic distribution, the PCC method outperforms the ECMP method. The PCC method can distribute traffic evenly across both ISP lines when downloading and uploading data packets. Meanwhile, the ECMP method can only carry out download and upload activities on one traffic path.