Performance Of Topology Research Articles

A Robust Multilevel Inverter Topology for Operation under Fault Conditions

Multilevel inverters (MLIs) are used on a large scale because they have low total harmonic distortion (THD) and low voltage stress across the switches, making them ideal for medium- and high-power applications. The authenticity of semiconductor devices is one of the main concerns for these MLIs to operate properly. Due to the large number of switches in multilevel inverters, the possibility of a fault also arises. Hence, a reliable five-level inverter topology with fault-tolerant ability has been proposed. The proposed topology can withstand an open-circuit (OC) fault caused when any single switch fails. In comparison to typical multilevel inverters, the proposed topology is fault-tolerant and reliable. The simulation of the proposed topology is conducted in MATLAB-Simulink and PLECS software packages, and the results obtained for normal pre-fault, during-fault, and after-fault conditions are discussed. Experimental results also prove the proposed cell topology’s robustness and effectiveness in tolerating OC faults across the switches. Furthermore, a thorough comparison is provided to demonstrate the proposed topology’s superiority compared to recently published topologies with fault-tolerant features.

Circuit Topology for Bottom-Up Engineering of Molecular Knots

The art of tying knots is exploited in nature and occurs in multiple applications ranging from being an essential part of scouting programs to engineering molecular knots. Biomolecular knots, such as knotted proteins, bear various cellular functions, and their entanglement is believed to provide them with thermal and kinetic stability. Yet, little is known about the design principles of naturally evolved molecular knots. Intra-chain contacts and chain entanglement contribute to the folding of knotted proteins. Circuit topology, a theory that describes intra-chain contacts, was recently generalized to account for chain entanglement. This generalization is unique to circuit topology and not motivated by other theories. In this conceptual paper, we systematically analyze the circuit topology approach to a description of linear chain entanglement. We utilize a bottom-up approach, i.e., we express entanglement by a set of four fundamental structural units subjected to three (or five) binary topological operations. All knots found in proteins form a well-defined, distinct group which naturally appears if expressed in terms of these basic structural units. We believe that such a detailed, bottom-up understanding of the structure of molecular knots should be beneficial for molecular engineering.

Probing topological spin liquids on a programmable quantum simulator.

Quantum spin liquids, exotic phases of matter with topological order, have been a major focus in physics for the past several decades. Such phases feature long-range quantum entanglement that can potentially be exploited to realize robust quantum computation. We used a 219-atom programmable quantum simulator to probe quantum spin liquid states. In our approach, arrays of atoms were placed on the links of a kagome lattice, and evolution under Rydberg blockade created frustrated quantum states with no local order. The onset of a quantum spin liquid phase of the paradigmatic toric code type was detected by using topological string operators that provide direct signatures of topological order and quantum correlations. Our observations enable the controlled experimental exploration of topological matter and protected quantum information processing.

Q-zip

Singularity editing of a quadrangle mesh consists in shifting singularities around for either improving the quality of the mesh elements or canceling extraneous singularities, so as to increase mesh regularity. However, the particular structure of a quad mesh renders the exploration of allowable connectivity changes non-local and hard to automate. In this paper, we introduce a simple, principled, and general quad-mesh editing primitive with which pairs of arbitrarily distant singularities can be efficiently displaced around a mesh through a deterministic and reversible chain of local topological operations with a minimal footprint. Dubbed Q-zip as it acts as a zipper opening up and collapsing down quad strips, our practical mesh operator for singularity editing can be easily implemented via parallel transport of a reference compass between any two irregular vertices. Batches of Q-zips performed in parallel can then be used for efficient singularity editing.

Infinite sum relations on universal C*-algebras

We extend the usual theory of universal C*-algebras from generators and relations in order to allow some relations to be described using the strong operator topology. In particular, we can allow some infinite sum relations. We prove a universal property for the algebras we define and we show how the Cuntz algebra of infinite isometries as well as the Exel-Laca algebras can be described using infinite sum relations. Finally, we give some sufficient conditions for when a C*-algebra generated by projections and partial isometries is a universal C*-algebra using only norm relations, in case one still wants to avoid using relations with respect to the strong operator topology.

Theta Omega Topological Operators and Some Product Theorems

We introduce and investigate the concepts of θ ω -limit points and θ ω -interior points, and we use them to introduce two new topological operators. For a subset B of a topological space Y , σ , denote the set of all limit points of B (resp. θ -limit points of B , θ ω -limit points of B , interior points of B , θ -interior points of B , and θ ω -interior points of B ) by D B (resp. D θ B , D θ ω B , Int B , Int θ B , and Int θ ω B ). Several results regarding the two new topological operators are given. In particular, we show that D θ ω B lies strictly between D B and D θ B and Int θ ω B lies strictly between Int θ B and Int B . We show that D B = D θ ω B (resp. Cl θ B = Cl θ ω B and D B = D θ ω B = D θ B ) for locally countable topological spaces (resp. antilocally countable topological spaces and regular topological spaces). In addition to these, we introduce several product theorems concerning metacompactness.

Linearized theory of the fluctuation dynamics in two-dimensional topological lasers

We theoretically study the collective excitation modes of a topological laser device operating in a single-mode steady-state with monochromatic emission. We consider a model device based on a two-dimensional photonic Harper-Hofstadter lattice including a broadband gain medium localized on the system edge. Different regimes are considered as a function of the value of the optical nonlinearity and of the gain relaxation time. The dispersion of the excitation modes is calculated via a full two-dimensional Bogoliubov approach and physically interpreted in terms of an effective one-dimensional theory. Depending on the system parameters, various possible physical processes leading to dynamical instabilities are identified and characterized. On this basis, strategies to enforce a stable single-mode topological laser operation are finally pointed out.

Stream Order Delineation using SRTM 30 meter Resolution Digital Elevation Model (DEM) and Hydrology Tools in ArcGIS 10.3 and QGIS: Mapping of Drainage Pattern of Mandi District, Himachal Pradesh, India

The paper describes step by step watershed and stream network delineation based on digital elevation models using the Hydrology tools in ArcGIS and online services for Hydrology and Hydrologic data. The 30-meter resolution SRTM image of Himachal Pradesh was downloaded from open topology website. This was further processed in QGIS and ArcGIS 10.3 software. The different hydrological processes and data management tools were used like, fill, Flow direction; flow accumulation, map algebra, stream orders, stream feature and stream dissolve in order to get the final map of Mandi drainage pattern.

Multi-task Transient Contingency Screening with Temporal Graph Convolutional Network in Power Systems

Rapid transient stability assessment (TSA) is an essential requirement for power system security. In real-world applications, transient contingency screening (TCS) applies TSA approaches to address the pre-defined contingency sets under online operation conditions. TSA by time domain simulation (TDS) is time-consuming, hence we propose a high-speed temporal graph convolutional network (TGCN) that achieves TSA decisions such that a large-scale contingency set can be scanned quickly with enough precision. Based on multi-graph inputs to reflect the transient process, the TGCN utilizes the graph convolutional network (GCN) to extract topology representations and temporal convolution (TC) layers to encode temporal relations. After above graph embedding, two downstream networks are designed for stability classification and critical generator prediction, respectively. Test results on IEEE 39 Bus system demonstrate its superiority over existing models under different operation topologies, fault locations and clearing modes.

Influence of heave plate topology on reaction force

In this study, we explore the role of heave plate topology on fluid reaction forces using three, representative shapes: a hexagonal flat plate, a hexagonal conic with an open top, and the same with a closed top that encloses a fluid mass. We force each test article sinusoidally in a quiescent tank and decompose the reaction force using forms of the Morison equation for phase-invariant and phase-dependent parameterizations. We find that a flat plate generates 5.3 % more fluid reaction force than the open conic topology, and 21.4% more than the enclosed conic. Asymmetric topologies generate asymmetric reaction forces, but the magnitude of asymmetry is limited by nearly symmetric fluid inertia forces, which dominate over drag for these test articles. Additionally, we observe asymmetric vortex dynamics for the flat plate when the Keulegan–Carpenter number is between 1 and 2, accompanied by a shift in the phase of the peak force by ≈7% of the oscillation period. As a consequence of this shift, the hydrodynamic coefficients estimated from the phase-dependent Morison equation decomposition are asymmetric, suggesting that phase-dependent representations may not provide physical insight in some hydrodynamic regimes.

The bi-compact-Gδ-open topology

This paper studies the bi-compact-[Formula: see text]-open topology on the family [Formula: see text] of all continuous functions from a completely regular space [Formula: see text] to the space [Formula: see text]. We compare this topology with open-point topology, bi-point-open topology and bi-compact-open topology and mention an example of a space asked in [P. Garg and S. Kundu, The compact-[Formula: see text]-open topology on [Formula: see text], Topology Appl. 159(8) (2012) 2082–2089] which satisfies [Formula: see text]. We also investigate submertrizability, mertrizability, separability, [Formula: see text]ech-completeness and Baire property of bi-compact-[Formula: see text]-open topology on [Formula: see text].

AToM: Active topology monitoring for the bitcoin peer-to-peer network

Over the past decade, the Bitcoin P2P network protocol has become a reference model for all modern cryptocurrencies. While nodes in this network are known, the connections among them are kept hidden, as it is commonly believed that this helps protect from deanonymization and low-level attacks. However, adversaries can bypass this limitation by inferring connections through side channels. At the same time, the lack of topology information hinders the analysis of the network, which is essential to improve efficiency and security. In this paper, we thoroughly review network-level attacks and empirically show that topology obfuscation is not an effective countermeasure. We then argue that the benefits of an open topology potentially outweigh its risks, and propose a protocol to reliably infer and monitor connections among reachable nodes of the Bitcoin network. We formally analyze our protocol and experimentally evaluate its accuracy in both trusted and untrusted settings. Results show our system has a low impact on the network, and has precision and recall are over 90% with up to 20% of malicious nodes in the network.

COMPUTING WATERTIGHT VOLUMETRIC MODELS FROM BOUNDARY REPRESENTATIONS TO ENSURE CONSISTENT TOPOLOGICAL OPERATIONS

Abstract. To simulate environmental processes, noise, flooding in cities as well as the behaviour of buildings and infrastructure, ‘watertight’ volumetric models are a measuring prerequisite. They ensure topologically consistent 3D models and allow the definition of proper topological operations. However, in many existing city or other geo-information models, topologically unchecked boundary representations are used to store spatial entities. In order to obtain consistent topological models, including their ‘fillings’, in this paper, a triangulation combined with overlay and path-finding methods is presented by climbing up the dimension, beginning with the wireframe model. The algorithms developed for this task are presented, whereby using the philosophy of graph databases and the Property Graph Model. Examples to illustrate the algorithms are given, and experiments are performed on a data-set from Erfurt, Thuringia (Germany), providing complex geometries of buildings. The heavy influence of double precision arithmetic on the results, in particular the positional and angular precision, is discussed in the end.

Magnetic Topology at Venus: New Insights Into the Venus Plasma Environment

AbstractThis study provides the first characterization of magnetic topology (i.e., the magnetic connectivity to the collisional ionosphere) at Venus, which might give new insights into the Venusian space environment on topics such as the penetration of the interplanetary magnetic field (IMF) into the ionosphere, planetary ion outflow and inflow, and auroral emission. Magnetic topology is inferred from the electron and magnetic field measurements from Venus Express. We demonstrate through a few case studies that various types of magnetic topologies exist at Venus, including typical draped IMF, open magnetic fields connected to the nightside atmosphere or the dayside ionosphere, and unexpected cross‐terminator closed field lines. We also provide a detailed characterization of an ionospheric hole event, where we find an open topology and a field‐aligned potential of V with respect to the collisional ionosphere, which has important implications for its formation mechanism.

Convergence Classes of L -Filters in L , M -Fuzzy Topological Spaces

An L , M -fuzzy topological convergence structure on a set X is a mapping which defines a degree in M for any L -filter (of crisp degree) on X to be convergent to a molecule in L X . By means of L , M -fuzzy topological neighborhood operators, we show that the category of L , M -fuzzy topological convergence spaces is isomorphic to the category of L , M -fuzzy topological spaces. Moreover, two characterizations of L -topological spaces are presented and the relationship with other convergence spaces is concretely constructed.

BIM Based Analysis of Spatial Properties in Building Layouts

We describe here methodologies for embedding geometric and topological operations in contemporary Building Information Modeling (BIM) Computer Aided Design (CAD) software, along with the computational implementation of domain specific evaluations; this is done to achieve the integration between spatial based spatial properties evaluations and architectural design workflows. This research describes methodologies and computational technologies used for the development of a computational design assistant in the context of laboratory buildings in Preliminary Concept Design (PCD), the geometric operations used for the creation of a prototype software are explained in their operation, and the architecture of said software is detailed.

Basic properties of 𝑋 for which the space 𝐶_{𝑝}(𝑋) is distinguished

In our paper [Proc. Amer. Math. Soc. Ser. B 8 (2021), pp. 86–99] we showed that a Tychonoff spaceXXis aΔ\Delta-space (in the sense of R. W. Knight [Trans. Amer. Math. Soc. 339 (1993), pp. 45–60], G. M. Reed [Fund. Math. 110 (1980), pp. 145–152]) if and only if the locally convex spaceCp(X)C_{p}(X)is distinguished. Continuing this research, we investigate whether the classΔ\DeltaofΔ\Delta-spaces is invariant under the basic topological operations.We prove that ifX∈ΔX \in \Deltaandφ:X→Y\varphi :X \to Yis a continuous surjection such thatφ(F)\varphi (F)is anFσF_{\sigma }-set inYYfor every closed setF⊂XF \subset X, then alsoY∈ΔY\in \Delta. As a consequence, ifXXis a countable union of closed subspacesXiX_isuch that eachXi∈ΔX_i\in \Delta, then alsoX∈ΔX\in \Delta. In particular,σ\sigma-product of any family of scattered Eberlein compact spaces is aΔ\Delta-space and the product of aΔ\Delta-space with a countable space is aΔ\Delta-space. Our results give answers to several open problems posed by us [Proc. Amer. Math. Soc. Ser. B 8 (2021), pp. 86–99].LetT:Cp(X)⟶Cp(Y)T:C_p(X) \longrightarrow C_p(Y)be a continuous linear surjection. We observe thatTTadmits an extension to a linear continuous operatorT^\widehat {T}fromRX\mathbb {R}^XontoRY\mathbb {R}^Yand deduce thatYYis aΔ\Delta-space wheneverXXis. Similarly, assuming thatXXandYYare metrizable spaces, we show thatYYis aQQ-set wheneverXXis.Making use of obtained results, we provide a very short proof for the claim that every compactΔ\Delta-space has countable tightness. As a consequence, under Proper Forcing Axiom every compactΔ\Delta-space is sequential.In the article we pose a dozen open questions.

Analysis of synchronous stability and control of multiplex oscillatory power network

The stability of synchronized state is essential for the stable operation and control of power network. This paper focuses on the multiplex oscillatory power network model, and then analyzes the stability of multiplex power network being comprised of Kuramoto oscillators. In specific, we infer the analytical important conditions for synchronous stability in a multiplex oscillatory power network. Furthermore, the adaptive controller is designed to achieve the frequency synchronization for multiplex power network. Combining analytical considerations with numerical simulations on small scale multiplex network, we address the synchronous stability and adaptive control in multiplex power network. In addition, we investigate synchronous cost of oscillatory power network via phase difference. It can be found that the synchronous cost of power network varies with different stable states. Therefore, our results can provide an innovative guide for adaptive control in conjunction with topology for stable operation.

Design and analysis of multiphase switched-capacitor coupled-inductor converter for high-gain DC-DC conversion

ABSTRACT This study presents an attractive closed-loop system of multiphase switched-capacitor coupled-inductor (MSCCI) converter as well as its relevant analysis and design to fulfill the task of high-gain DC-DC conversion/regulation. The power part of MSCCI is structurally composed of a three-stage switched-capacitor (SC) booster and a turn-ratio-n coupled inductor. Under multiphase operation, the step-up gain can be uplifted into just by using fewer circuit elements, where is the duty cycle. When ,, it can lift the output into 44 times voltage of supply theoretically. While raising n or , a bigger gain will be realised but it may result in the serious volume size or magnetic bias of coupled inductor. Here, the stage number of SC booster can be extendable for an additional gain to reduce these tensions. The control part is constructed by a non-overlapping circuit, phase generator, and pulse-width-modulation (PWM) compensator, so as to execute the topological multiphase operation and also increase the output regulation/robustness. Some theoretical analysis and control design are discussed. Finally, the validity of the analysis/design is examined via simulation results, and the practicality of this proposed converter is confirmed via experiments on the prototype circuit.

Non-invertible global symmetries and completeness of the spectrum

It is widely believed that consistent theories of quantum gravity satisfy two basic kinematic constraints: they are free from any global symmetry, and they contain a complete spectrum of gauge charges. For compact, abelian gauge groups, completeness follows from the absence of a 1-form global symmetry. However, this correspondence breaks down for more general gauge groups, where the breaking of the 1-form symmetry is insufficient to guarantee a complete spectrum. We show that the correspondence may be restored by broadening our notion of symmetry to include non-invertible topological operators, and prove that their absence is sufficient to guarantee a complete spectrum for any compact, possibly disconnected gauge group. In addition, we prove an analogous statement regarding the completeness of twist vortices: codimension-2 objects defined by a discrete holonomy around their worldvolume, such as cosmic strings in four dimensions. We discuss how this correspondence is modified in various, more general contexts, including non-compact gauge groups, Higgsing of gauge theories, and the addition of Chern-Simons terms. Finally, we discuss the implications of our results for the Swampland program, as well as the phenomenological implications of the existence of twist strings.