Ring Topology Research Articles

A Multiobjective Particle Swarm Optimizer Using Ring Topology for Solving Multimodal Multiobjective Problems

This paper presents a new particle swarm optimizer for solving multimodal multiobjective optimization problems which may have more than one Pareto-optimal solution corresponding to the same objective function value. The proposed method features an index-based ring topology to induce stable niches that allow the identification of a larger number of Pareto-optimal solutions, and adopts a special crowding distance concept as a density metric in the decision and objective spaces. The algorithm is shown to not only locate and maintain a larger number of Pareto-optimal solutions, but also to obtain good distributions in both the decision and objective spaces. In addition, new multimodal multiobjective optimization test functions and a novel performance indicator are designed for the purpose of assessing the performance of the proposed algorithms. An effectiveness validation study is carried out comparing the proposed method with five other algorithms using the benchmark functions to prove its effectiveness.

Synthesis of N−H Bearing Imidazolidinones and Dihydroimidazolones Using Aza‐Heck Cyclizations

AbstractThe synthesis of unsaturated, unprotected imidazolidinones via an aza‐Heck reaction is described. This palladium‐catalyzed process allows for the cyclization of N‐phenoxy ureas onto pendant alkenes. The reaction has broad functional group tolerance, can be applied to complex ring topologies, and can be used to directly prepare mono‐ and bis‐unprotected imidazolidinones. By addition of Bu4NI, dihydroimidazolones can be accessed from the same starting materials. Improved conditions for preparing unsaturated, unprotected lactams are also reported.

Synthesis of N-H Bearing Imidazolidinones and Dihydroimidazolones Using Aza-Heck Cyclizations.

The synthesis of unsaturated, unprotected imidazolidinones via an aza-Heck reaction is described. This palladium-catalyzed process allows for the cyclization of N-phenoxy ureas onto pendant alkenes. The reaction has broad functional group tolerance, can be applied to complex ring topologies, and can be used to directly prepare mono- and bis-unprotected imidazolidinones. By addition of Bu4 NI, dihydroimidazolones can be accessed from the same starting materials. Improved conditions for preparing unsaturated, unprotected lactams are also reported.

Global genetic learning particle swarm optimization with diversity enhancement by ring topology

Genetic learning particle swarm optimization (GL-PSO) improves the performance of particle swarm optimization (PSO) by breeding superior exemplars to guide the motion of particles. However, GL-PSO adopts a global topology for exemplar generation and cannot preserve sufficient diversity to enhance exploration, and therefore, its performance on complex optimization problems is unsatisfactory. To further improve GL-PSO's performance and adaptability, two modifications are incorporated into the original GL-PSO. A ring topology is adopted in exemplar generation to enhance diversity and exploration, while a global learning component (GLC) with linearly adjusted control parameters is employed to improve the algorithm's adaptability. The resultant algorithm is referred to as global genetic learning particle swarm optimization with diversity enhancement by ring topology (GGL-PSOD). To validate the effectiveness of these two modifications, they are combined with GL-PSO separately and together and further tested experimentally. The comparison results on the CEC2017 test suite show that the adoption of the ring topology in exemplar generation can enhance the diversity and exploration capability of GL-PSO, while combining GLC alone with GL-PSO cannot achieve significant improvement. Incorporating both modifications into GL-PSO, the resultant GGL-PSOD exhibits high performance and strong adaptability on different types of CEC2017 functions. It outperforms seven representative PSO variants and five non-PSO meta-heuristics, including GL-PSO, SL-PSO, HCLPSO, EPSO, ABC, CMA-ES and CS.

White Rabbit HSR: A Seamless Subnanosecond Redundant Timing System With Low-Latency Data Capabilities for the Smart Grid

New smart grid and industrial-Internet-of-things (IIoT) directions require accurate synchronization features to capture, trigger, and manage events in industrial networks with the best possible precision and accuracy. The implementation of redundancy features for time and data distribution to increase fault tolerance, together with an enhancement of the availability of the network services such as generic object-oriented substation events, become mandatory due to their critical nature. For these reasons, the authors of this paper presented a new challenging approach covering the industrial standards requirements regarding timing and availability through the development of mechanisms that make possible the avoidance of single point of failure in ring topologies. This approach uses the White Rabbit (WR) as the main timing distribution technology, able to synchronize devices below 1 ns. Moreover, the development of a mechanism able to change from a primary to a backup time reference in approximately zero time with an observed maximum phase shift of 170 ps implies an important qualitative leap with respect to IIoT and the smart grid (e.g., phasor measurement units). This paper addresses the development and results of the high-availability seamless redundancy protocol for the WR technology to conform a leading-edge deterministic and reliable ultraaccurate timing system with high-availability data features for industrial facilities in accordance with IEC 61850 and IEC 62439-3.

Compressive sensing and random walk based data collection in wireless sensor networks

Data collection is one of the most important research topics in wireless sensor networks. Compressive sensing can break through the classical Shannon–Nyquist boundary and reduce the total energy consumption. Random walk technology has a significant advantage in the energy balance. Random walk based compressive sensing data collection mechanism is a combination of these two technologies, which reinforce complementary advantages. However, the traditional scheme faces two challenges, i.e., large transmission energy consumption caused by the overlong multi-hop transmission path and the low recovery accuracy caused by poorly designed compressive sensing measurement. In this paper, we propose a ring topology based compressive sensing data collection scheme (RTCS). The total number of hops is reduced by a ring topology based random walk. The recovery accuracy is improved by the dual compensation based compressive sensing measurement. The theoretical analysis, as well as the experimental evaluation obtained from two different network deployment environments, demonstrates that the proposed scheme can achieve the performance superior to the most closely related work.

On‐chip communication for neuro‐glia networks

Hardware has become more prone to faults as a result of geometric scaling, wear-out and faults caused during the manufacturing process, therefore, the reliability of hardware is reliant on the need to continually adapt to faults. A computational model of biological self-repair in the brain, derived from observing the role of astrocytes (a glial cell found in the mammalian brain), has captured self-repair within models of neural networks known as neuro-glia networks. This astrocyte-driven repair process can address the issues of faulty synapse connections between neurons. These astrocyte cells are distributed throughout a neuro-glia network and regulate synaptic activity, and it has been observed in computational models that this can result in a fine-grained self-repair process. Therefore, mapping neuro-glia networks to hardware provides a strategy for achieving self-repair in hardware. The internal interconnecting of these networks in hardware is a challenge. Previous work has focused on addressing neuron to astrocyte communication (local), however, the global self-repair process is dependent on the communication infrastructure between astrocyte-to-astrocyte; e.g. astrocyte network. This study addresses the key challenge of providing a scalable communication interconnect for global astrocyte network requirements and how it integrates with existing local communication mechanism. Area/power results demonstrate scalable implementations with the ring topology while meeting timing requirements.

Coarse-Grained Molecular Simulation and Nonlinear Manifold Learning of Archipelago Asphaltene Aggregation and Folding.

Asphaltenes constitute the heaviest aromatic component of crude oil. The myriad of asphaltene molecules falls largely into two conceptual classes: continental-possessing a single polyaromatic core-and archipelago-possessing multiple polyaromatic cores linked by alkyl chains. In this work, we study the influence of molecular architecture upon aggregation behavior and molecular folding of prototypical archipelago asphaltenes using coarse-grained molecular dynamics simulation and nonlinear manifold learning. The mechanistic details of aggregation depend sensitively on the molecular structure. Molecules possessing three polyaromatic cores show a higher aggregation propensity than those with two, and linear archipelago architectures more readily form a fractal network than ring topologies, although the resulting aggregates are more susceptible to disruption by chemical dispersants. The Yen-Mullins hierarchy of self-assembled aggregates is attenuated at high asphaltene mass fractions because of the dominance of promiscuous parallel stacking interactions within a percolating network rather than the formation of rodlike nanoaggregates and nanoaggregate clusters. The resulting spanning porous network possesses a fractal dimension of 1.0 on short length scales and 2.0 on long length scales regardless of the archipelago architecture. The incompatibility of the observed assembly behavior with the Yen-Mullins hierarchy lends support that high-molecular weight archipelago architectures do not occur at significant levels in natural crude oils. Low-dimensional free energy surfaces discovered by nonlinear dimensionality reduction reveal a rich diversity of metastable configurations and folding behavior reminiscent of protein folding and inform how intramolecular structures can be modulated by controlling asphaltene mass fraction and dispersant concentration.

Multiterminal DC Transmission Systems Based on Superconducting Cables Feasibility Study, Modeling, and Control

This paper deals with the appropriate modeling and control strategy of a multiterminal dc transmission (MTDC) system that incorporates high-temperature superconducting (HTS) dc cables. The system is based on voltage source converters for the interconnection of stiff ac grids. An overview of the high voltage direct current power transfer technology along with the possibilities it enables, as well as an introduction to the concept of multiterminal topology are presented. The operation principles of the superconducting technology are described and the control strategy of HTS-based MTDC networks is presented. To validate the performance and the dynamic response of the system under steady state as well as under fault and load change conditions, a typical four-terminal MTDC network in ring topology is developed in MATLAB/Simulink.

Design of a mission network system using SpaceWire for scientific payloads onboard the Arase spacecraft

Arase is a small scientific satellite program conducted by the Institute of Space and Astronautical Science/Japan Aerospace Exploration Agency, which is dedicated to the detailed study of the radiation belts around Earth through in situ observations. In particular, the goal is to directly observe the interaction between plasma waves and particles, which cause the generation of high-energy electrons. To observe the waves and particles in detail, we must record large volumes of burst data with high transmission rates through onboard mission network systems. For this purpose, we developed a high-speed and highly reliable mission network based on SpaceWire, as well as a new and large memory data recorder equipped with a data search function based on observation time (the time index, TI, is the satellite time starting from when the spacecraft is powered on.) with respect to the orbital data generated in large quantities. By adopting a new transaction concept of a ring topology network with SpaceWire, we could secure a redundant mission network system without using large routers and having to suppress the increase in cable weight. We confirmed that their orbit performs as designed.

Oscillation Modes in Symmetrical Wireless-Locked Systems

Time synchronization of multiple elements of a wireless network can be achieved through the wireless coupling of their oscillator circuits. Most previous works on wireless locking of oscillators analyze the system in an idealized manner, representing the oscillator elements with phase models and describing the propagation effects with constant scalar coefficients and time delays. Here, a realistic analysis of the wireless system is presented, which relies on the extraction of the oscillator models from harmonic-balance (HB) simulations and takes into account the antenna gains and propagation effects. The most usual network configurations, corresponding to ring, fully connected, and star topologies, are investigated in detail. In symmetric conditions, the oscillation modes are detected through an eigenvalue/eigenvector calculation of an equivalent coupling matrix. For each particular mode, the system is analyzed in the following manners: by means of an analytical formulation, able to provide all the coexistent solutions, and through a circuit-level HB simulation of an equivalent system with a reduced number of oscillator elements. The stability properties are determined by means of a perturbation system of general application to any coupled structure. A specific formulation is also derived to predict the impact of discrepancies between the oscillator elements. All the results have been validated with independent circuit-level simulations and measurements.

Grey wolf optimizer with cellular topological structure

Grey wolf optimizer (GWO) is a newly developed metaheuristic inspired by hunting mechanism of grey wolves. The paramount challenge in GWO is that it is prone to stagnation in local optima. This paper proposes a cellular grey wolf optimizer with a topological structure (CGWO). The proposed CGWO has two characteristics. Firstly, each wolf has its own topological neighbors, and interactions among wolves are restricted to their neighbors, which favors exploitation of CGWO. Secondly, information diffusion mechanism by overlap among neighbors can allow to maintain the population diversity for longer, usually contributing to exploration. Empirical studies are conducted to compare the proposed algorithm with different metaheuristics such as success-history based adaptive differential evolution with linear population size reduction (LSHADE), teaching-learning based optimization algorithm (TLBO), effective butterfly optimizer with covariance matrix adapted retreat phase (EBOwithCMAR), novel dynamic harmony search (NDHS), bat-inspired algorithm (BA), comprehensive learning particle swarm optimizer (CLPSO), evolutionary algorithm based on decomposition (EAD), ring topology PSO (RPSO), crowding-based differential evolution (CDE), neighborhood based crowding differential evolution (NCDE), locally informed particle swarm (LIPS), some improved variants of GWO and GWO. Experimental results show that the proposed method performs better than the other algorithms on most benchmarks and engineering problems.

Linear multi-objective drift analysis

The tools of drift analysis enable bounds on run-times (or first hitting times) of stochastic processes, such as randomised algorithms, based on bounds on the expected progress at each time step in terms of a distance measure. In this paper, we generalise the multiplicative drift theorem to apply to processes which are best described by more than one distance function. We provide four examples to illustrate the application of this method: the run-time analysis of an evolutionary algorithm on a multi-objective optimisation problem; the analysis of a variant of the voter model on a network; a parallel evolutionary algorithm taking place on islands with limited migration; a synchronous network epidemiology model. In the latter example, we show that populations with limited neighbourhoods (such as the ring topology) are able to resist epidemics much more effectively than well-mixed populations.

A novel tangent-ring TWDM metro-access optical network featuring reconfiguration and reliability

In this paper, we propose a novel tangent-ring TWDM metro-access network providing flexible reconfiguration and high reliability. With the innovate design of flexible distribution node (FDN) and distributed control mechanism (DCM), three kinds of reconfigurable TWDM-PONs can be built to achieve efficient intra and inter ONU direct communication by reusing optical distribution network (ODN). In addition, three-level protections covering both feeder and distribution fibers are also separately supported by the use of optical switches and natural advantage of single-fiber tangent ring topology. Moreover, with the use of simplified RN* and ONU*, the proposed network can upgrade smoothly and achieve pay-as-you grow. The network capacity, OSNR, cost and transmission performances are also studied, which suggests that this network has a good performance.

Routing and wavelength assignment for exchanged crossed cubes on ring-topology optical networks

The exchanged crossed cube, denoted by $$\textit{ECQ}(s, t)$$ , is a novel graph with fewer edges and smaller diameter compared to other variations of the corresponding hypercube. The ring topology, denoted by $$R_n$$ , is one of the most popular topologies in Wavelength division multiplexing optical networks. This paper addresses the routing and wavelength assignment problem for realizing $$\textit{ECQ}(s, t)$$ communication pattern on $$R_n$$ , where $$n=s+t+1$$ . We propose an embedding scheme. Base on the embedding scheme, a wavelength assignment algorithm using $$2^{s+t-2}+\lfloor 2^t/3\rfloor $$ wavelengths is devised. We show that the wavelength assignment algorithm uses no more than 1.25 times of wavelengths compared to the optimal wavelength number, i.e., it is a factor 1.25 approximation algorithm. Moreover, the number of additional required wavelengths is no more than $$\lfloor 2^{t-1}/3\rfloor $$ .

Scheduling in Multi-Wavelength Ring-Based Optical Networks-on-Chip

Synchronous networks-on-chip (NoC) require tailored schedulers achieving low latency, high throughput, and fairness while avoiding packet collisions. Efficient schedulers exist for rearrangeable non-blocking NoC. However, NoCs fabricated in integrated photonics typically suffer a blocking behavior due to the limitations of the switching capabilities in the space and wavelength domains. This paper discusses a scheduler for an integrated optical NoC based on a ring topology and realized with multiple resonating microrings (multi-microring, MMR). Scheduling in MMR architecture consists of the conventional matching sub-problem and the wavelength assignment sub-problem. The paper’s contribution is twofold. An iterative parallel wavelength matching (iPWM) algorithm is presented for jointly addressing both sub-problems. iPWM achieves performance similar to a two-step scheduler based on sequential iSLIP and first-fit wavelength assignment, but with a computational complexity lower than and independent of the number of wavelengths. A comprehensive comparison with the two-step scheduler based on the more complex maximum weighted matching algorithm and with an optimal scheduler is also carried out for the case of fixed and tunable transmitters to assess the trade-off between scheduling complexity and performance. In addition, bidirectionality with one or two transceivers per port is proposed as a way to overcome the throughput degradation caused by the blocking behavior. Simulation results indicate that bidirectionality is very effective in improving the throughput and reducing the latency even when using a single transceiver.

Application of Neural Network for Testing Selected Specification Parameters of Voltage-Controlled Oscillator

In this paper, the application of the Artificial Neural Network (ANN) algorithm has been used for testing selected specification parameters of voltage-controlled oscillator. Today, mixed electronic circuits specification time is an issue. An analog part of Phase Locked Loop is a voltage-controlled oscillator, which is very sensitive to variation of the technology process. Fault model for the integrated circuit voltage control oscillator (VCO) in ring topology is introduced and the before test stage classificatory is designed. In order to reduce testing time and keep the specification accuracy (approximation) on the high level, an artificial neural network has been applied. The features selection process and output coding for specification parameters are described. A number of different ANN have been designed and then compared with real specification of the VCO. The results obtained gives response in short time with high enough accuracy.

P-Median based formulations with backbone facility locations

In this paper, we propose new mixed integer linear programming (MILP) models for the p-Median problem subject to ring, tree and star backbone topology constraints on the facility locations. More precisely, we minimize simultaneously the total connection cost distances between customers and facilities, and cost distances among facilities when connected under a ring, tree or a star network topology. In principle, all our proposed models can be used in any application related with the classical p-Median problem. Application examples include wired and wireless network design, computer networks, transportation, water supply and electrical networks, just to name a few. The proposed models arise as a combination of the classical p-Median problem with the traveling salesman, spanning tree, and star network problems, respectively. We prove the correctness of each proposed model. Then, we further propose variable neighborhood search (VNS) meta-heuristic algorithms, one for each topology. Our numerical results indicate that the ring models are harder to solve with CPLEX than the tree and star ones. Whilst VNS algorithms proved to be highly efficient when compared to the optimal solutions of the problem for small, medium and large size instances. Moreover, we obtain better feasible solutions than CPLEX for the large instances and in significantly less computational cost.

Evaluation of Virtual Operating Systems and Switches under Ring, Star and Tree Topologies for Streaming Large Data Sets

This paper discusses architectural performance of virtual operating switches, and systems under various topological structures to handle packet deliveries of large streaming and dynamic data sets. The topology structures studied include: tree, fully connected mesh, and star. A virtual network framework is developed that can generate any number of nodes with reconfigurable parameters. An evaluation on memory requirements, disk-space, and CPU usage on three different virtual network switches (openvSwitch, openSwitch, openWRT) were also investigated. Two specific protocols–Routing Information Protocol (RIP) and Open Shortest Path First (OSPF) are tested against bandwidth requirements.

SANS Study of Ring Topology Effects on the Miscibility of Polymer Blends

Highly purified hydrogenous ring poly(4-trimethylsilylstyrene) (h-PT) and deuterated ring polyisoprene (d-PI) samples as well as their linear counterparts were prepared, and the miscibility of three kinds of polymer blends, i.e., linear–linear, ring–linear, and ring–ring, denoted as L–L, R–L, and R–R, respectively, with all 50/50 vol % was evaluated by small angle neutron scattering (SANS) measurements. PT and PI are known as a miscible polymer pair with lower critical solution temperature (LCST) type phase diagram. At low-q regime of the scattering profiles, R–R blend exhibits much higher scattering intensity than L–L and R–L, while the latter two show similar profiles. Moreover, from Zimm’s analysis, the spinodal temperature of R–R was estimated to be about 100 °C lower than the other two blends, L–L and R–L. These results suggest that the miscibility of R–R is considerably lower than the other two blends, which is a clear manifestation of the topological effect on the phase behavior of the present blend.