Topological Modifications Research Articles

Fast Mesh Reconstruction from Single View Based on GCN and Topology Modification

3D reconstruction based on single view aims to reconstruct the entire 3D shape of an object from one perspective. When existing methods reconstruct the mesh surface of complex objects, the surface details are difficult to predict and the reconstruction visual effect is poor because the mesh representation is not easily integrated into the deep learning framework; the 3D topology is easily limited by predefined templates and inflexible, and unnecessary mesh self-intersections and connections will be generated when reconstructing complex topology, thus destroying the surface details; the training of the reconstruction network is limited by the large amount of information attached to the mesh vertices, and the training time of the reconstructed network is too long. In this paper, we propose a method for fast mesh reconstruction from single view based on Graph Convolutional Network (GCN) and topology modification. We use GCN to ensure the generation of high-quality mesh surfaces and use topology modification to improve the flexibility of the topology. Meanwhile, a feature fusion method is proposed to make full use of the features of each stage of the image hierarchically. We use 3D open dataset ShapeNet to train our network and add a new weight parameter to speed up the training process. Extensive experiments demonstrate that our method can not only reconstruct object meshes on complex topological surfaces, but also has better qualitative and quantitative results.

Modeling of tool load for optimization of tool life in diagonal generating grinding

Diagonal continuous generating grinding with ceramic bonded wheels is commonly used for hard finishing of automotive gears with topological modifications. In this process, areas of the grinding wheel have to be used repeatedly to machine multiple components, resulting in not achieving the same tool life as conventional generating grinding. This paper presents a detailed process model predicting loads on the wheel as a basis for an optimization of tool life. Based on a redistribution of the roughing and shifting areas of the grinding wheel, significantly lower wear could be demonstrated in tests.

A flexible topological flank modification method based on polynomial interpolation function

A flexible topological flank modification method based on polynomial interpolation function

Errata: A flexible topological flank modification method based on polynomial interpolation function [Journal of Advanced Mechanical Design, Systems, and Manufacturing, Vol. 17, No. 3 (2023), JAMDSM0041

Errata: A flexible topological flank modification method based on polynomial interpolation function [Journal of Advanced Mechanical Design, Systems, and Manufacturing, Vol. 17, No. 3 (2023), JAMDSM0041

Direct Charge Control for Mixed Conduction Mode Grid-Connected Inverter

Discontinuous conduction mode (DCM) for inverters can lower the size of filter inductors and can realize the soft switching for switches. However, the current stress under the DCM is high. Aiming to solve this problem, this article uses a T-type three-level circuit to construct an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> -type grid-connected inverter, which introduces the trapezium conduction mode (TPCM) with the zero-voltage switching to lower the current stress when the grid current is large. Both the DCM and the TPCM can work at a fixed switching frequency, but it is difficult to design controllers using the conventional average state model. To address this challenge, this article proposes a charge quantity model (CQM) that is applicable to any inverter topology and conduction mode, where the output charge quantity of the bridge is used as a control variable. The proposed model represents a linear two-order model, which can greatly simplify controller design. Based on the CQM, a direct charge control method working at a fixed switching frequency is developed, which combines a PID regulator and a feedforward controller of the grid voltage. The excellent steady-state and dynamic control performances of the proposed model and control method are verified by simulations and experiments.

Three-Phase Hybrid Converter With Simultaneous DC and AC Outputs

A novel topology of three-phase hybrid converter (TP-HC) which can supply simultaneously both DC and AC loads is presented. This topology is obtained by adding three switches to T-type three-level inverter. Consequently, this converter can achieve one group of DC/DC power transformation and another three-phase three-level AC voltage outputs with adjustable amplitude. The topology and operation modes of the proposed hybrid converter are introduced. Then the working principle and the available switching states of converter are analyzed, including current path, output phase voltage level and blocking voltage of different switching states. The characteristics of three typical hybrid converters are compared. A strategy combining time-sharing modulation and virtual space vector modulation (VSVPWM) is adopted to realize simultaneous DC and AC outputs of the converter. Then the capacitance voltage balance of the DC link is realized. In order to simplify the modulation strategy, a carrier based on pulse width modulation (CBPWM)strategy is proposed. Then, boost ratio of this converter is analyzed in detail. Finally, the feasibility of the proposed topology and the effectiveness of modulation strategy are verified by simulation and experiment.

Influence of Wide-swath Machining Error on Transmission Error of Topological Modification Gear Transmission System

Influence of Wide-swath Machining Error on Transmission Error of Topological Modification Gear Transmission System

Simulative Study of the Applicability of Topological Modifications for Gear Skiving

Simulative Study of the Applicability of Topological Modifications for Gear Skiving

Construction and Application of Distributed Power Storage System

In today’s society, with the continuous development of China’s economy, the power industry is also growing rapidly. As an important part of the logistics distribution system, the warehousing system plays an important role in the production and operation of the entire enterprise. Therefore, effective utilization of distributed generation is of great significance for improving energy supply efficiency and reducing operating costs. This paper mainly introduces the background and application status of distributed generation technology, analyzes and discusses the research and simulation of power supply network scheduling optimization methods based on DGS structure model and DGs topology mode, and gives the corresponding solutions. After the design of the system, this paper conducts a performance test on the system to determine whether the system can operate normally. The test results show that the performance of the distributed power storage system is basically stable at more than 80% under different power storage capacities, and the power utilization efficiency is also more than 90%. This shows that the performance of the power storage system can meet the needs of users.

Developing multi‐path routing protocol in MANET using hybrid SM‐CSBO based on novel multi‐objective function

SummaryOne of the infrastructure‐free networks is mobile ad hoc networks (MANETs) that are built with limited battery life using wireless mobile devices. This restricted battery capability in MANETs creates the necessity of considering the energy‐awareness constraint in designing them. As routing protocols, the major aim of MANETs is to create the energy awareness in the network; it improves the network's lifetime through effectively utilizing the available restricted energy. Moreover, it creates some limitations like the mobility constraint, wireless link's sensitivity to environmental impacts, and restricted transmission range and residual energy of nodes that causes rapid modifications in the network topology and frequent link failure. By taking those problems, this paper plans to develop a new multipath routing protocol, where the hybrid optimization algorithm with the integration of cuckoo search optimization (CSO) and butterfly optimization algorithm (BOA) is proposed and named sensory modality‐based cuckoo search butterfly optimization (SM‐CSBO) for determining the optimal path between the source and destination. The main goal is to select the path with better link quality and more stable links to guarantee reliable data transmission. The multi‐objective function is considered with the factors regarding distance, normalized energy, packet delivery ratio, and control overhead to develop an effective routing protocol in MANET. The proposed model of SM‐CSBO algorithm has superior than 5.8%, 30.4%, 36.7%, and 39.3%, correspondingly maximized than PSO, SFO, CSO, and SFO algorithms while considering the number of nodes as 150. The simulation outcomes proved that it enhances network performance when compared with the other traditional protocols.

Fluorine and sodium depletion followed by refractive index modification imprinted on fluorophosphate glass surface by thermal poling

Thermal poling using microstructured electrodes on oxyfluoride glasses have been investigated and the impact on optical properties was evaluated. A micrometer refractive index modification based on the sodium and fluorine migration has been evidenced, through the creation of a layer with different chemical composition as compared to the original glass. Topological and optical properties modifications after poling treatment are discussed. For the first time, we described the migration of negative fluorine ion in the direction of the cathode from the glass network. Na and F migration led to a layer richer in oxides with a strong contrast of + 0.06 of the refractive index in the imprinted structures.

In situ interfacial nanoengineering of imidazole-bridged one-dimensional AgVO3 nanoribbons by Ag fractals

The major bottleneck in harnessing the potential of solid-solid interfacial hetero structures involves incoherent interface constructions and complicated synthesis approaches. In this context, a synthesis strategy involving in situ interfacial manipulation of imidazole-bridged one-dimensional single-crystalline nanoribbons is developed through the dynamic growth of Ag fractals. This article successfully demonstrates structural and morphological changes in the monoclinic patterns of silver vanadate nanoribbons with Wulf constructions. These are associated with in situ electron beam perturbations and can be attributed to β-phase silver vanadate crystals. The dynamics and topological modifications induced on the nanohybrid interfaces mechanistically suggest the ability of the novel hybrid interfaces in harnessing and storing photogenerated auxiliary charge carriers. The synthesis methodology used enables in overcoming major bottleneck in nanoengineering of solid-solid interfacial heterostructures by using real-time feedback of the imaging e-beam to precisely fabricate these heterostructures and study the interface transition.

High power non-electrolytic capacitor LED driver with three ports based on energy distribution

To eliminate the influence of electrolytic capacitors on the driving life of high-power LED, a three-port high-power LED without electrolytic capacitor driving power supply based on energy distribution is proposed. The energy difference between the input terminal and the output terminal is balanced by the auxiliary DC-DC circuit to reduce the ripple of the output current. The working principle of the topology and switching mode is analyzed in detail. According to the proposed circuit topology, the mechanism of the output current ripple of the low-frequency circuit is analyzed, and a low-frequency ripple control strategy suitable for the circuit topology is proposed. The specific implementation scheme and the key parameters of the circuit design are given, and the model is verified, which proves that the proposed model is feasible.

Improved algorithm of tooth surface topological modification and nonlinear dynamic analysis of herringbone gears

This paper presents an improved algorithm of herringbone gear's tooth surface topological modification based on overlap ratio, and the superiority of improved topology modification gear pair is verified from two aspects of statics and dynamics. Firstly, the static analysis is carried out to verify that the improved topology modification gear pair has good static performance. Secondly, time-varying mesh stiffness (TVMS) and static transmission error of modified herringbone gear pair are calculated by slice method, and the change of contact state is considered. Thirdly, taking dynamic meshing force as the main factor affecting the change of contact state, the dynamic model of the modified gear pair is improved. Finally, dynamic equations are solved by numerical method, and the nonlinear dynamic performance of herringbone gear pair under three cases of no modification, traditional topology modification, and improved topology modification are compared. The results show that compared with the traditional topology modification, the improved topology modification can make the load share between teeth of the gear pair more uniform. And the nonlinear dynamic performance of the gear pair after improved topology modification is better than that of the traditional topology modification gear pair.

Calculation of gear mesh stiffness and loaded tooth contact analysis based on ease-off surface topology

Based on the theory of rack-gear common-tangential conjugate generating, the constructing of ease-off surface has been done by means of the topology modification of polynomial surface. By analyzing topological structure characteristics of ease-off surface, the meshing characteristics such as the contact area, the contact line, and transmission error are determined. By using the geometric analysis of ease-off surface and the potential energy method, the calculation methods of gear tooth stiffness and loaded transmission error are given, and a series of results for the tooth meshing stiffness, loaded transmission error, and load distribution map under varied loads are obtained. In order to solve the stress problem of tooth surface edge contact, the calculation method of quasi-Hertz contact is proposed by subdividing finite contact elements. Taking the second-order parabolic topological modification as an example, the time-varying history characteristics of tooth surface meshing are analyzed. The simulation results of the maximum contact stress and contact area are in good agreement with those calculated by MASTA software. Based on the integration of the geometric analysis of ease-off surface, the tooth stiffness calculation of potential energy method and the quasi-Hertz contact, it provides a convenient method for loaded tooth contact analysis.

Propagating Design Updates to Structured Analysis Meshes

Generating structured meshes is often an expensive process, limiting the use of high-fidelity numerical simulation methods for design, especially when the design is not yet fixed and design updates are likely. For hexahedral meshes generated by decomposing a B-Rep model into regions for which simple meshing strategies are known, robustly propagating design modifications to the decomposed representation and subsequent mesh is very challenging. In this paper, an approach is presented to propagate parametric update and feature changes to structured meshes. Geometric and topological modifications on the design model are identified first, enabling the equivalent modifications to be identified on the decomposition of the design model. Virtual topology operations used to generate the initial decomposition are combined with the meshing constraints of individual sub-regions to update the decomposition and associated mesh locally. The approach is demonstrated for a number of design updates.

An analytical method to control and predict grinding textures on modified gear tooth flanks in CNC generating gear grinding

• A method to control and predict gear surface texture is proposed. • Both dressing and grinding motions are considered in generating gear grinding. • Oblique direction of texture patterns on gear tooth flanks is adjustable and predictable. • Gear tooth topology modification with oblique grinding texture is achievable. Natural motion in generating gear grinding often produces regular and mutually-parallel gear grinding texture, which induces higher pure-tone gear meshing noise than that with an irregular texture generated by gear honing. This study presents a generation method of irregular and oblique grinding texture on modified gear tooth flanks considering both dressing and grinding motions in a CNC generating gear grinder. The grinding texture is controllable via an additional installation angle between the grinding wheel and the work gear axes. Meanwhile, the gear tooth flank deviation caused by this variation is corrected by additional motions of machining axes . The sensitivity matrix (SM) combined with the Levenberg-Marquardt (LM) algorithm is employed to determine the additional motion functions. In numerical examples, effects of axial feeding speed, abrasive grain size, and installation angle variation on texture patterns and their mean roughness are investigated, respectively. A crowned tooth flank with irregular and oblique grinding texture is also demonstrated to prove the reasonability and validity of the proposed method.

High-Definition High-Bandwidth DC/AC Power Conversion Through Binary Asymmetric Cascaded H-Bridges

It is known that cascaded H-bridges with heterogenous module voltages can, in theory, generate exponentially-refined output voltage levels and achieve high output resolutions from only one power source. However, several critical considerations have yet to be thoroughly studied, namely the controllability of module voltages under any load conditions, and how to schedule the switching states optimally. We present a scheduling algorithm and topological modifications for binary asymmetric cascaded H-bridges (ACHBs) to achieve complete sensorless operation under any load conditions while using only one power source. The scheduling algorithm cancels the energy intake of floating modules per time frame, while low-power auxiliary dc/dc circuits, which naturally emerge from the bridge structure, can correct any voltage drift without the need for voltage sensors. Rigorous analyses reveal an inherent performance tradeoff between reference-tracing accuracy and floating module voltage controllability for ACHBs in general, for which the proposed algorithm always achieves the Pareto front. The proposed ACHB and the algorithm are tested on an experimental setup with six modules and 65 output levels (i.e., effectively six bits).

Analysis of tooth contact for cylindrical gear with high-order topological modification and misalignment

The tooth contact analysis model is introduced for cylindrical gear with high-order topological modification and misalignment. According to the generation principle of gear, the tooth surface equation of double-crowned gear by using worm grinding wheel is derived. Based on the gear meshing theory, a tooth contact model of cylindrical gear considering errors and high-order topological modification is established. Taking helical gears as an example, the effects of errors and four different combinations of modification curves on the contact marks and transmission errors of tooth surface were analyzed. Results show that the paths of contact change dramatically with different combinations of modification curves. With the increasing of the order of modification curve, the contact path transitions smoothly in the middle of the tooth width, while the total length of the major axis of the contact ellipses increase significantly compared with taking the quadratic parabola modification. With proper parameters of the modification, the apex of transmission error function is flatter and its amplitude decreases which further reduces the vibration of gear transmission to installation error. The finite element method is applied to validate the proposed analysis model. The results are basically consistent and the maximum error is within 3.5 %.

Bilayer graphene kirigami

Since the experimental demonstration of the kirigami technique for graphene in 2015, several studies have been conducted exploring its diverse impacts in the properties and behavior of graphene. However, because most of the studies have focused on monolayer graphene, the implications of a bilayer graphene kirigami (BGK) remain poorly understood, especially regarding its mechanical response. Here, we employ a newly developed machine learning potential available in the literature to study the mechanical properties and characteristics of BGK by using molecular simulations. The effects of different cutting and stacking patterns are revealed, showing a highly stretchable material with capacity of enhancing the maximum strain by a factor of eight as compared to pristine graphene. During deformation, a large out-of-plane displacement is evidenced, along with a topological modification at the ripping interface composed of eight-membered rings. Also, a distinct structure formation is found, described as horizontally-aligned arrays of interconnected nanotubes, with capability of being employed in environments that require increased compression resistance, and further potential to serve as building blocks for complex 3D structures.