Unified Topology Research Articles

Effect of different vortex models on the linear instability characteristics of wingtip vortex

Different analytical vortex models have been developed to characterize the evolution of wingtip vortex. However, their effect on the instability characteristics has not been well recognized. In this paper, the wingtip vortex generated by an elliptical wing was first experimentally measured in the near-wake and far-wake regions by particle image velocimetry. Then, it was fitted to different one-scale and multiscale vortex models as the base flow for linear stability analysis. The results show that though the eigenvalue spectra by different vortex models exhibit a unified topology with an isolated point around ωi=0 and three continuous branches, the multiscale vortex models tend to overestimate the instability of the wingtip vortex nonphysically. Furthermore, structures of the most unstable eigenmodes (Mode C) also differ between one-scale and multiscale vortex models. On this basis, a meaningful parameter, penetration depth (dp), is defined to predict the instability behavior of one perturbation mode. It is found that the most unstable streamwise wavenumber coincides with the streamwise wavenumber, where 1−dp is the local minimum, regardless of vortex models. The negative correlation between ωi and 1−dp of Mode C indicates that the closer the perturbation vorticity to the vortex boundary, the larger the growth rate. This reminds us that the penetration length might be a candidate measure of the instability behavior of perturbation modes, which deserves to be further studied in a broader parameter space.

DreamFace: Progressive Generation of Animatable 3D Faces under Text Guidance

Emerging Metaverse applications demand accessible, accurate and easy-to-use tools for 3D digital human creations in order to depict different cultures and societies as if in the physical world. Recent large-scale vision-language advances pave the way for novices to conveniently customize 3D content. However, the generated CG-friendly assets still cannot represent the desired facial traits for human characteristics. In this paper, we present Dream-Face, a progressive scheme to generate personalized 3D faces under text guidance. It enables layman users to naturally customize 3D facial assets that are compatible with CG pipelines, with desired shapes, textures and fine-grained animation capabilities. From a text input to describe the facial traits, we first introduce a coarse-to-fine scheme to generate the neutral facial geometry with a unified topology. We employ a selection strategy in the CLIP embedding space to generate coarse geometry, and subsequently optimize both the detailed displacements and normals using Score Distillation Sampling (SDS) from the generic Latent Diffusion Model (LDM). Then, for neutral appearance generation, we introduce a dual-path mechanism, which combines the generic LDM with a novel texture LDM to ensure both the diversity and textural specification in the UV space. We also employ a two-stage optimization to perform SDS in both the latent and image spaces to significantly provide compact priors for fine-grained synthesis. It also enables learning the mapping from the compact latent space into physically-based textures (diffuse albedo, specular intensity, normal maps, etc.). Our generated neutral assets naturally support blendshapes-based facial animations, thanks to the unified geometric topology. We further improve the animation ability with personalized deformation characteristics. To this end, we learn the universal expression prior in a latent space with neutral asset conditioning using the cross-identity hypernetwork, we subsequently train a neural facial tracker from video input space into the pre-trained expression space for personalized fine-grained animation. Extensive qualitative and quantitative experiments validate the effectiveness and generalizability of DreamFace. Notably, DreamFace can generate realistic 3D facial assets with physically-based rendering quality and rich animation ability from video footage, even for fashion icons or exotic characters in cartoons and fiction movies.

Unified Multiple Constant Multipliers for Dynamic Exchange of Low-Precision Kernels on FPGAs

Recent work has shown that small, fast, and power-efficient multiple constant multiplication (MCM) implementations can be realized on FPGAs rather than requiring specialized embedded multipliers. However, the limited silicon area on FPGAs requires applications such as image processing to frequently exchange the multiplier (filter) blocks in a series of filtering operations, and no previous works have considered the MCM problem under topological constraint to avoid time-consuming partial reconfiguration on FPGAs. In this paper, we define a unified MCM (UMCM) problem of finding a unified hardware topology for the multiplier blocks frequently exchanged and introduce a framework termed compatible graph synthesis to solve the problem efficiently. Using a set of parameters to logarithmic shifters, dynamic exchange of multiplier blocks with the unified topology can be realized without partial reconfiguration on FPGAs. Experimental results show that the solution is valuable for applications that require frequent exchange of multiplier blocks on FPGAs due to a limited silicon area budget.

A Unified Topology for the Integration of Electric Vehicle, Renewable Energy Source, and Active Filtering for the Power Quality Improvement of the Electrical Power Grid: An Experimental Validation

Electrical power grids are facing challenges concerning new linked technologies and associated contributions of power electronics, both regarding innovative topologies of power converters and advanced power management algorithms. Additionally, technologies related to renewables and electric mobility have several points in common, especially about the interface with the power grid, which allows to foresee a convergence for unified solutions in the power grid interface, without jeopardizing the functionalities and added values of each technology. Encompassing this purpose, this paper presents a unified topology, based on a three-phase structure, which, in addition to a collaborative operation with the power grid targeting the compensation of power quality problems, also enables the integration of a renewable energy source and an electric vehicle. The main contribution of this paper resides in the fact that only an interface with the power grid is necessary to involve three central features of smart grids: renewables, electric mobility, and power quality. Overall, the unified topology presents a four-quadrant structure, both in the perspective of AC and DC interfaces, offering multiple functionalities, mainly to the power grid. In the AC interface, the structure operates in interleaved mode, while in the DC interface, the structure operates in multilevel mode. The global control algorithm is presented, covering the interconnection between the mentioned technologies, as well as the details of implementation of the individual control algorithms regarding each interface. A laboratory prototype, connected to a three-phase 400 V-50 Hz power grid, was used to obtain an experimental validation for a maximum operating power of 12.5 kW, corroborating the essential advantage characteristics and the correct functioning of the presented unified topology.

Reliability of computer structures of integrated modular avionics for hardware configurations

The problem of designing advanced computing systems in the class of structures of integrated modular avionics is considered. The unified topology of the internal network of the computer on the basis of Space Wire exchange channels and variants of its execution for various onboard applications is offered. Equivalent reliability schemes of each of the specific structures are introduced and the probabilities of trouble-free operation of each structure are analyzed. Families of graphic dependencies are given. The analysis of the existing principles and algorithms for testing multiprocessor multimodal onboard digital computer systems is given; the new testing algorithm for the multiprocessor systems which follows the software design standards for products of integrated modular avionics is offered. The structure of the unified automated workplace for checking the functional modules of integrated modular avionics is considered. Specific requirements inherent in the workplaces for testing integrated avionics are identified: an increased level of control of the hardware component of products; the ability to simulate the failure state of individual components of avionics to check the mode of reconfiguration of the computer system; modular construction of software with the division of verification tests into components performed at the level of each CPM and the computer as a whole in single-task and multitasking modes; openness of architecture of a workplace, which provides an ability to change the level of control complexity of a product and control of one class of complexity; intra-project unification of both hardware and software of the workstation of the inspection.

A unified topology approach to dot-, rod-, and sheet-MOFs

<h2>Summary</h2> Metal-organic frameworks made from multi-metal-ion units in the shape of clusters and rods (termed dot-MOFs and rod-MOFs) are well known. Here, we introduce MOFs with multi-metallic units in the form of sheets—sheet-MOFs. We show exemplars of all three types of units based on structures containing Y³⁺, Ce³⁺, or Gd³⁺ linked by benzene-1,2,4,5-tetracarboxylate to give crystals of a dot-MOF in H₂NMe₂[Y(btec)(H₂O)] <b>CTH-14</b>, a sheet-MOF in [Ce₃(btec)(Hbtec)(OAc)(HCO₂)] <b>CTH-15</b>, and a rod-MOF in 4,4′-azopyridinium[Gd₂(btec)₂] <b>CTH-16</b>. Cyclic voltammetry shows that <b>CTH-15</b> stabilizes Ce(IV). Given the fact that sheet-MOFs represent an intellectual advance in the evolution of MOFs, a unified approach is proposed for the topological classification of dot-, rod-, and sheet-MOFs. It is suggested that the stability of MOFs follow in the trend dot < rod < sheet. For CTH-14-16, the sheet- and the rod-MOF have higher thermal stability. We suggest sheet-MOFs as an additional strategy for making robust MOFs.

A Topology Synthetization Method for Single-Phase, Full-Bridge, Transformerless Inverter with Leakage Current Suppression—Part II

This paper proposes a topology derivation methodology to achieve small leakage current or zero leakage current for photovoltaic application. The core of the proposed method is a unified topology model and MN principle to show how to derive all possible topologies based on unipolar sinusoidal pulse width modulation (USPWM) and double-frequency USPWM (DFUSPWM). Part II of this paper discusses the topology synthetization method to achieve zero leakage current. Two types of neutral point clamped (NPC) topologies based on USPWM and DFUSPWM are elaborated. Two possible connections for the NPC cell are introduced, and detailed NPC topology derivation procedures are also provided. All existing NPC topologies are derived, and twenty-two new NPC topologies are found based on the new topology derivation methodology for a single-phase, full-bridge, transformerless inverter.

CRIC: Computing Resource Information Catalogue as a unified topology system for a large scale, heterogeneous and dynamic computing infrastructure

CRIC is a high-level information system which provides flexible, reliable and complete topology and configuration description for a large scale distributed heterogeneous computing infrastructure. CRIC aims to facilitate distributed computing operations for the LHC experiments and consolidate WLCG topology information. It aggregates information coming from various low-level information sources and complements topology description with experimentspecific data structures and settings required by the LHC VOs in order to exploit computing resources. Being an experiment-oriented but still experiment-independent information middleware, CRIC offers a generic solution, in the form of a suitable framework with appropriate interfaces implemented, which can be successfully applied on the global WLCG level or at the level of a particular LHC experiment. For example there are CRIC instances for CMS[11] and ATLAS[10]. CRIC can even be used for a special task. For example, a dedicated CRIC instance has been built to support transfer tests performed by DOMA Third Party Copy working group. Moreover, extensibility and flexibility of the system allow CRIC to follow technology evolution and easily implement concepts required to describe new types of computing and storage resources. The contribution describes the overall CRIC architecture, the plug-in based implementation of the CRIC components as well as recent developments and future plans.

Automatic statistical volume element modeling based on the unified topology model

Needs for new particle based heterogeneous materials as led to the development of many Statistical Volume Element (SVE) modeling schemes tailored to specific shapes of particles or meshing procedures. To generalize the numerical analysis of particle filled SVEs, a modeling methodology based on the Unified Topology Model (UTM) is proposed. Using the concept of Boundary Representation (BRep) and a modified Random Sequential Adsorption (RSA) algorithm, the geometry of a Statistical Volume Element (SVE) can be generated automatically with any shape of particles. Using an integration of Computer-Aided Design (CAD) and mesh tools, a mesh size map is constructed with the objective of minimizing the number of mesh elements while preserving quality of the discretization. The SVE is meshed using proven CAD model meshing algorithms for a robust and reliable result. Simulation and post processing are carried out automatically, without any user interaction. To illustrate the potential of this new method, a short glass fiber / epoxy matrix composite is modeled with spherical and elongated cylindrical particles.

Systematic design and realization of double-negative acoustic metamaterials by topology optimization

Double-negative acoustic metamaterials (AMMs) offer the promising ability of superlensing for applications in ultrasonography, biomedical sensing and nondestructive evaluation. However, the systematic design and realization of broadband double-negative AMMs are stilling missing, which hinder their practical implementations. In this paper, under the simultaneous increasing or non-increasing mechanisms, we develop a unified topology optimization framework involving different microstructure symmetries, minimal structural feature sizes and dispersion extents of effective parameters. The optimization framework is applied to conceive the heuristic resonance-cavity-based and space-coiling metamaterials with broadband double negativity. Meanwhile, we demonstrate the essences of double negativity derived from the novel artificial multipolar LC (inductor-capacitor circuit) and Mie resonances which can be induced by controlling mechanisms in optimization. Furthermore, abundant numerical simulations validate the corresponding double negativity, negative refraction, enhancement of evanescent waves and subwavelengh imaging. Finally, we experimentally show the desired broadband subwavelengh imaging by using the 3D-printed optimized space-coiling metamaterial. The present design methodology provides an ideal approach for constructing the constituent “atoms” of metamaterials according to any artificial physical and structural requirements. In addition, the optimized broadband AMMs and superlens lay the structural foundations of subwavelengh imaging technology.

Unified topology and joint types optimization of general planar linkage mechanisms

We propose a gradient-based topology optimization method to synthesize a planar linkage mechanism consisting of links and revolute/prismatic joints, which converts an input motion to a desired output motion at its end effector. Earlier gradient-based topology optimization methods were mainly applicable to the synthesis of linkage mechanisms connected by revolute joints only. The proposed method simultaneously determines not only the topology of planar linkage mechanisms but also the required revolute and/or prismatic joint types. For the synthesis, the design domain is discretized into rectangular rigid blocks that are connected to each other by the newly proposed revolute and prismatic joint elements, the joint states of which vary depending on the corresponding design variables. The new concept of joint elements is materialized thorough an elaborately configured set of zero-length springs whose stiffnesses vary as the functions of the design variables. Therefore, any connectivity state among unconnected, rigidly connected, revolute joint, and prismatic joint states can be represented by properly adjusting the stiffnesses. After presenting our modeling, formulation, and sensitivity analysis, the developed method is tested with verification examples. Then the developed method is extended to be able include additional shape design variables and applied to solve a realistic problem of synthesizing a finger rehabilitation robotic device. We expect the developed method to play a critical role in synthesizing a wide class of general linkage mechanisms.

Systematic Design and Realization of Double-Negative Acoustic Metamaterials by Topology Optimization

Double-negative acoustic metamaterials (AMMs) offer the promising ability of superlensing for applications in ultrasonography, biomedical sensing and nondestructive evaluation. However, the systematic design and realization of broadband double-negative AMMs is stilling missing, which hinders their practical implementations. In this paper, under the simultaneous increasing or non-increasing mechanisms, we develop a unified topology optimization framework involving the different microstructure symmetries, minimal structural feature sizes and dispersion extents of effective parameters. The optimization framework is applied to discover the heuristic resonance-cavity-based and space-coiling metamaterials with broadband double negativity. Meanwhile, we demonstrate the essences of double negativity derived from the novel artificial multipolar LC (inductor-capacitor circuit) and Mie resonances which can be induced by controlling mechanisms in optimization. Furthermore, abundant numerical simulations validate the corresponding double negativity, negative refraction, enhancements of evanescent waves and subwavelengh imaging. Finally, we experimentally show the desired broadband subwavelengh imaging by using the 3D-printed optimized space-coiling metamaterial. The present design methodology provides an ideal approach for constructing the constituent atoms of metamaterials according to any manual physical and structural requirements. In addition, the optimized broadband AMMs and superlens can truly lay the structural foundations of subwavelengh imaging technology.

On weak topology for optimal control of switched nonlinear systems

Optimal control of switched systems is challenging in general due to the discrete nature of the switching control input. One of the most well-known approaches is the embedding based method which addresses this challenge by solving a relaxed optimization problem with only continuous inputs and then projecting the relaxed solution back to obtain a solution to the original problem. In this paper, we present a unified topology based framework for analyzing and designing various embedding based switched optimal control algorithms. The proposed framework views the embedding based approaches from a novel topological perspective as a change of topology over the optimization space. A general procedure of constructing different switched optimal control algorithms with guaranteed convergence to a stationary point is described. Numerical examples are also provided to illustrate the effectiveness of the proposed framework.

Reliability Evaluation of Integrated Modular Avionics Computational Structures for Different Hardware Configurations

The problem of designing advanced computing systems of integrated modular avionics is considered in this paper. A unified topology of internal network based on SpaceWire channels and options for its application for a variety of onboard implementations are proposed. Equivalent reliability scheme of each special structure is provided and the fail-safe performance probability of each structure is analyzed.

스마트 그리드 망을 위한 IEC61970/IEC61850 통합 정보 모델과 토폴로지 모델 설계

The smart grid, which is an integrated type of the power system and the digital network, requires the integration of a CIM(Common Information Model) standard for information modelling at the power control centers and an IEC 61850 standard for automation at the substation level in order to efficiently exchange the information between system elements. This paper describes the method of data transfer from one standard information model to the other standard unified information model by mapping between the objects of IEC 61850 and IEC61970 CIM standards both in the static and dynamic models, and designs the method of data transfer and information exchange between the topology processing application using unified topology class packages.

Material interpolation schemes for unified topology and multi-material optimization

This paper presents two multi-material interpolation schemes as direct generalizations of the well-known SIMP and RAMP material interpolation schemes originally developed for isotropic mixtures of two isotropic material phases. The new interpolation schemes provide generally applicable interpolation schemes between an arbitrary number of pre-defined materials with given (anisotropic) properties. The method relies on a large number of sparse linear constraints to enforce the selection of at most one material in each design subdomain. Topology and multi-material optimization is formulated within a unified parametrization.

On Topology Reconfiguration for Defect-Tolerant NoC-Based Homogeneous Manycore Systems

Homogeneous manycore systems are emerging for tera-scale computation and typically utilize Network-on-Chip (NoC) as the communication scheme between embedded cores. Effective defect tolerance techniques are essential to improve the yield of such complex integrated circuits. We propose to achieve fault tolerance by employing redundancy at the core-level instead of at the microarchitecture level. When faulty cores exist on-chip in this architecture, however, the physical topologies of various manufactured chips can be significantly different. How to reconfigure the system with the most effective NoC topology is a relevant research problem. In this paper, we first show that this problem is an instance of a well known NP-complete problem. We then present novel solutions for the above problem, which not only maximize the performance of the on-chip communication scheme, but also provide a unified topology to Operating System and application software running on the processor. Experimental results show the effectiveness of the proposed techniques.

Unified Multi-Phase Modeling and Topology Optimization for Complex Vibro-Acoustic Systems consisting of Acoustic, Elastic and Poroelastic Media

This talk introduces the UMP (Unified Multi-Phase) modeling method, recently developed for the streamlined analysis and systematic design of complex vibro-acoustic systems. The main difference between the conventional method and the UMP method is that the latter uses the same governing equations for all acoustic components while the former, different equations for different acoustic components. The UMP approach also treats all interface conditions by a unified formulation unlike the conventional approach. Consequently, physically different components and various interface conditions are treated by a unified multi-phase model along with unified interface conditions. The key in this approach is to realize that Biot’s equations for poroelastic media can degenerate to the Helmholtz equation or the elastodynamic equations if some of poroelastic material coefficients are properly controlled and that the interface conditions for poroelastic-poroelastic media can also degenerate to those for interfaces of any similar/dissimilar media. Since any reduction in the degrees of primary field variables in degenerated systems can cause numerical singularity, some of the poroelastic coefficients are slightly perturbed from the exact limit values in representing the degenerated systems. The unified approach becomes extremely useful when an iterative design process requiring interface evolutions at every iteration step is implemented as in the topology optimization of complex vibro-acoustic systems.

A comparison of techniques for geometry access related to mesh generation

One of the major issues of mesh generation today is access to geometry in an accurate and efficient manner. This paper will review several of the issues associated with accessing geometry for mesh generation. This paper will also evaluate alternative techniques for accessing geometry and review how these techniques address, or do not address, the issues related to geometry access for mesh generation. The techniques for geometry access to be reviewed include: translation and healing, discrete representations, direct geometry access, and unified topology accessing geometry directly. The intent of this paper is to provide an overview to the alternative approaches and how they address the specific issues related to accessing geometry for mesh generation. It is not the intent of this paper to provide detailed algorithms related to accessing or repairing geometry data.

Unified topology design of static and vibrating structures using multiobjective optimization

Since structural design is usually required to perform in more than one environment, the ability to consider multiple objectives has to be included within the framework of topology optimization. A unified topology design methodology is proposed to generate structures satisfying both static and vibration performance measures using the multiobjective optimization approach. The weighted sum of conflicting objectives resulting from the norm method is used to generate the optimal compromise solutions, and the decision function is set to select the preferred solution. The objective function is defined by the mean compliance and mean eigenvalue to design a flexible structure which meets both the static and vibration requirements. The optimality conditions of the bicriteria problem are derived based on the modified optimality criteria method. To substantiate this approach, illustrated examples are presented both for verification and application.