Ring Topology Research Articles

Michael-type cyclizations in lantibiotic biosynthesis are reversible.

Lanthipeptides are members of the ribosomally synthesized and post-translationally modified peptides (RiPPs). They are generated in two biosynthetic steps: dehydration of Ser and Thr residues to the corresponding dehydroamino acids and subsequent conjugate addition by the thiol of Cys residues to generate the characteristic lanthionine and methyllanthionine thioether-bridged structures. Typically, a lanthipeptide contains multiple thioether cross-links. Recent studies have proposed that the final ring topology may be under thermodynamic control. If so, then the Michael-type cyclization reaction would need to be reversible, but such reversibility has never been demonstrated. We show here for the class I lanthipeptide cyclase NisC and class II lanthipeptide synthetase HalM2 that, indeed, the conjugate addition reactions are reversible and that the enzymes can open up all thioether rings in their products. We also propose that a His residue that is conserved among the lanthipeptide cyclases acts as the acid or base that protonates or generates the enolate intermediate during thioether ring formation and opening, respectively.

Robustness Analysis Based on Optical Fiber Sensor Networks Topology

Although optical fiber sensor networks (OFSNs) attract more and more attentions, they are still facing the problem of lacking the methods for assessing network robustness quantitatively. This paper improves the recently presented OFSNs robustness evaluation model by proposing the robustness error assessment based on Monte Carlo method. Robustness simulations of several network topologies, including line, ring, star, bus, and double ring topologies, have been done with the model, proving that the concentric double ring topology proposed by Fernandez-Vallejo et al. is more robust than the other four topologies. Parameters required for robustness calculation in ring topology are listed in detail. Then, an experimental robustness assessment approach is established. According to it, eight-point fiber Bragg grating sensor networks with the four basic topologies are employed. Support vector machine is applied to process data. Both threshold and attenuation coefficient have been gotten from experiments. Comparison between experimental and simulative robustness verifies the practicability of the robustness evaluation method, and also proves that ring and star topologies are better than the others, whereas bus topology is unfit for improving robustness by adding sensors.

RPNoC: A Ring-Based Packet-Switched Optical Network-on-Chip

Optical network-on-chip (ONoC) is a promising solution for its high bandwidth and low energy consumption. However, optical circuit switching requires an electrical control network, which leads to network congestion, low network utilization, high latency, and an overhead in energy consumption. In this letter, we propose an architecture called RPNoC based on ring topology using packet switching. A wavelength assignment method and a deadlock-free deterministic routing algorithm are jointly designed, which significantly reduce the maximum number of hops using much fewer optical devices compared with other packet-switched ONoCs. The simulation is carried out for 64-node RPNoC under uniform and realistic traffic pattern. The evaluation results show that it yields higher throughput, lower latency, and lower energy consumption than mesh and ring networks.

A new class of consensus protocols for agent networks with discrete time dynamics

The paper introduces a new class of consensus protocols to reach an agreement in networks of agents with discrete time dynamics. In order to guarantee the convergence of the proposed algorithms, some general results are proved in the framework of non-negative matrix theory. Moreover, we characterize the set of the consensus protocols and we specify the algorithm that each agent has to employ. Furthermore, we show that in the case of balanced graphs, the agents can apply the consensus protocols by a decentralized and scalable computation. The convergence properties are studied by a set of tests that show the good performance of the proposed algorithm for different network topologies, even in the cases in which the standard protocols do not exhibit satisfying performances. In particular, a rigorous theoretical analysis of the proposed protocol convergence for networks with ring topology is provided and compared with the standard algorithm.

Deployment of a Tensegrity Footbridge

Deployable structures are structures that transform their shape from a compact state to an extended in-service position. Structures composed of tension elements that surround compression elements in equilibrium are called tensegrity structures. Tensegrities are good candidates for deployable structures since shape transformations occur by changing lengths of elements at low energy costs. Although the tensegrity concept was first introduced in 1948, few full-scale tensegrity-based structures have been built. Previous work has demonstrated that a tensegrity ring topology is potentially a viable system for a deployable footbridge. This paper describes a study of a near-full-scale deployable tensegrity footbridge. The study has been carried out both numerically and experimentally. The deployment of two modules (one half of the footbridge) is achieved through changing the length of five active cables. Deployment is aided by energy stored in low stiffness spring elements. Self-weight significantly influences deployment, and deployment is not reproducible using the same sequence of cable- length changes. Active control is thus required for accurate positioning of front nodes in order to complete deployment through joining both sides at center span. Additionally, testing and numerical analyses have revealed that the deployment behavior of the structure is nonlinear with respect to cable-length changes. Finally, modeling the behavior of the structure cannot be done accurately using friction-free and dimension- less joints. Similar deployable tensegrity structures of class two and higher are expected to require simulation models that include joint dimensions for accurate prediction of nodal positions. DOI: 10.1061/(ASCE)ST.1943-541X.0001260 . © 2015 American Society of Civil Engineers.

Process variability-induced NoC link failure: A probabilistic model

As technology scales down, the amount of process variations increases causing Networks-on-Chip (NoC) links, designed to be identical, to have current and delay variations. Thus, some links may fail to meet design timing or power constraints. Using current and delay variations with design constraints, we estimate link failure probability across NoC links. Modeling results show that the average NoC link failure probability across a 4×4 mesh reaches 3.3% for voltage mode (VM) links and 3.7% for current mode (CM) links at 32nm. The average NoC link failure probability also increases as the supply voltage decreases or the operating frequency increases. As NoC mesh size scales from 4×4 to 8×8, the link failure probability doubles to 8% for VM links at 22nm. Topology evaluation shows that for small NoC size, the grid topology outperforms the tree one with lower amount of variation. On the other hand, for relatively large NoC sizes, the hierarchical tree and ring topologies outperform the grid topology with lower amount of variations across the links.

Studying Fault-Tolerance in Island-Based Evolutionary and Multimemetic Algorithms

The use of parallel and distributed models of evolutionary algorithms (EAs) is widespread nowadays as a means to improve solution quality and reduce computational times when solving hard optimization problems. For this purpose, emergent computational environments such as P2P networks and desktop grids are offering a plethora of new opportunities but also bring new challenges: functioning on a computational network whose resources are volatile requires fault tolerance and resilience to churn. In this work we analyze these issues from the point of view of island-based EAs. We consider two EA variants, genetic and multimemetic algorithms, and analyze the impact on them of design decisions regarding the logical interconnection topology among islands and the particular fault-management policy used. To be precise, we have conducted an extensive empirical evaluation of five topologies (ring, von Neumann grid, hypercube and two kinds of scale-free networks) and four policies (including checkpoint creation and population reinitialization variants) on four benchmark problems, considering three different scenarios of increasing resource volatility. The statistical analysis of the results underlines the inherent fault-tolerance of these EAs and indicates that, while checkpointing is the most robust strategy and is superior in the most fragile topologies, a seemingly simpler guided reinitialization strategy provide statistically comparable results on the top-performing topologies, namely von Neumann grids and hypercubes.

Latency and Traffic Reduction for Process-Level Network in Smart Substation based on High-availability Seamless Redundancy

Process-level communication network brings digital technology to the high-voltage switchyard, a major stage in the evolution to ensure the protection control and data acquisition of smart substation. This network requires a mission-critical protocol such as high-availability seamless redundancy (HSR). Two main drawbacks of HSR, however, are the transmission latency introduced by each hop in the single ring (SR) topology and the unnecessary traffic due to the duplicated copies of sending frames. This study presents two enhanced solutions and fully implements quick removing (QR) approach to HSR for improving the latency and reducing the traffic volume in process-level network. The main idea of these two enhanced solutions is to reduce the minimum number of hops required for delivery messages to destinations for reducing the maximum end-to-end latency (ML). To achieve traffic reduction, the QR approach is concretized in HSR nodes for fully applying to any closed-loop HSR networks. Performance of IEC 61850-based process bus networks are analyzed theoretically and demonstratively by Network Simulator-2 (NS-2) and OPNET Modeler®. The combination of enhanced solutions and the QR algorithm solves both main drawbacks of HSR, improving the network performance optimally. These enhancements of HSR are applicable to not only on substation automation networks, but also to any real-time industrial networks.

Optimal Multi-TDMA Scheduling in Ring Topology Networks

A scheduling algorithm will be proposed for wireless ring topology networks, utilizing time division multiple access (TDMA) with possible simultaneous operation of nodes. The proposed algorithm finds the optimal schedule to minimize the turnaround time for messages in the network. The properties of the algorithm are mathematically analyzed and proven, and practical test results are also provided.

Self-Healing Hybrid Protection Architecture for Passive Optical Networks

Expanding size of passive optical networks (PONs) along with high availability expectation makes the reliability performance a crucial need. Most protection architectures utilize redundant network components to enhance network survivability, which is not economical. This paper proposes new self-healing protection architecture for passive optical networks (PONs), with a single ring topology and star-ring topology at feeder and distribution level respectively. The proposed architecture provides desirable protection to the network by avoiding fiber duplication at both feeder and distribution level. Moreover, medium access control (MAC) controlled switching is utilized to provide efficient detection, and restoration of faults or cuts throughout the network. Analytical analysis reveals that the proposed self-healing hybrid protection architecture ensures survivability of the affected traffic along with desirable connection availability of 99.9994 % at minimum deployment cost, through simple architecture and simultaneous protection against failures.

A Optimization Traffic Grooming Algorithm Based on Bidirectional SONET Ring Topology Network

The issue of WDM network traffic grooming has been a hot in the field of research. The implementation of traffic grooming technology can improve the utilization of wavelength channels, reducing the link delay and the blocking rate of the network, which to improve network resource utilization and optimize network performance. This article mainly studies all-optical network routing algorithm utilizing WDM technology to achieve the dynamic traffic grooming and propose a optimization grooming policy -HaffmanGroom (M) algorithms which based on SONET / WDM ring network. The most important feature of this algorithm is that the SONET / WDM ring network of multiple multicast request packet , with a minimum weight of the light path priority selection method, the flow of requests each group effectively optimize ease . The algorithm takes into account the impact of the link request factor and link hops to optimize the link selection. The simulation results show that under the conditions of factors and the number of hop a request fully consider the impact of these two factors to the link, and can achieve optimal link with the smallest weights for effective data transmission, improving resource utilization, reducing blocking rate in order to achieve the purpose of optimizing network performance.

Four wave mixing power suppression in hybrid network topology using optical phase conjugation module

In this paper, four wave mixing (FWM) power suppression in the case of hybrid network topology is carried out and analyzed. The hybrid network topology consists of bus and ring topologies. In this investigation the optical phase conjugation (OPC) based method is considered as an approach to suppress the FWM power. From the results it is observed that using OPC module the FWM power suppression over 40dBm can be achieved.

Shape versus porosity: A systematic survey of cobalt oxide nanosheet calcination from 200 to 900 °C

A wide range of Co3O4 nanoshapes has been synthesized by calcinations, all from the same precursor to distinguish the influence of porosity and shape, which has been determined by image recognition algorithms analyzing many particles. We survey morphology transitions, crystallinity (single- to poly- to single-crystalline again), porosity, and electrochemical capacity from 200 to 900°C. A maximally porous structure is confirmed near 300°C. A steep capacitance decline is due to loss of pore access. Capacitance is shown to decline further because the shape changes, with only 39% being due to lost porosity. This decline is surprisingly linear with 0.65F/(g°C) over 500°C, although the shapes even pass through a ring topology, likely from a kinetic Kirkendall mechanism.

Dynamical behaviors in time-delay systems with delayed feedback and digitized coupling

We consider a network of delay dynamical systems connected in a ring via unidirectional positive feedback with constant delay in coupling. For the specific case of Mackey–Glass systems on the ring topology, we capture the phenomena of amplitude death, isochronous synchronization and phase-flip bifurcation as the relevant parameters are tuned. Using linear stability analysis and Master Stability Function approach, we predict the region of amplitude death and synchronized states respectively in the parameter space and study the nature of transitions between the different states. For a large number of systems in the same dynamical configuration, we observe splay states, mixed splay states and phase locked clusters. We extend the study to the case of digitized coupling and observe that these emergent states still persist. However, the sampling and quantization reduce the regions of amplitude death and induce phase-flip bifurcation.

Quantum phase transitions in networks of Lipkin-Meshkov-Glick models.

We study the quantum critical behavior of networks consisting of Lipkin-Meshkov-Glick models with an anisotropic ferromagnetic coupling. We focus on the low-energy properties of the system within a mean-field approach and the quantum corrections around the mean-field solution. Our results show that the weak-coupling regime corresponds to the paramagnetic phase when the local field dominates the dynamics, but the local anisotropy leads to the existence of an exponentially degenerate ground state. In the strong-coupling regime, the ground state is twofold degenerate and possesses long-range magnetic ordering. Analytical results for a network with the ring topology are obtained.

High divergence of the precursor peptides in combinatorial lanthipeptide biosynthesis.

Lanthionine-containing peptides (lanthipeptides) are a rapidly growing family of polycyclic peptide natural products belonging to the large class of ribosomally synthesized and post-translationally modified peptides (RiPPs). These compounds are widely distributed in taxonomically distant species, and their biosynthetic systems and biological activities are diverse. A unique example of lanthipeptide biosynthesis is the prochlorosin synthetase ProcM from the marine cyanobacterium Prochlorococcus MIT9313, which transforms up to 29 different precursor peptides (ProcAs) into a library of lanthipeptides called prochlorosins (Pcns) with highly diverse sequences and ring topologies. Here, we show that many ProcM-like enzymes from a variety of bacteria have the capacity to carry out post-translational modifications on highly diverse precursor peptides, providing new examples of natural combinatorial biosynthesis. We also demonstrate that the leader peptides come from different evolutionary origins, suggesting that the combinatorial biosynthesis is tied to the enzyme and not a specific type of leader peptide. For some precursor peptides encoded in the genomes, the leader peptides apparently have been truncated at the N-termini, and we show that these N-terminally truncated peptides are still substrates of the enzymes. Consistent with this hypothesis, we demonstrate that about two-thirds of the ProcA N-terminal sequence is not essential for ProcM activity. Our results also highlight the potential of exploring this class of natural products by genome mining and bioengineering.

Surface induced dissociation yields substructure of Methanosarcina thermophila 20S proteasome complexes

Native mass spectrometry (MS) and surface induced dissociation (SID) have been applied to study the stoichiometry and quaternary structure of non-covalent protein complexes. In this study, Methanosarcina thermophila 20S proteasome, which consists of four stacked heptameric rings (α7β7β7α7 symmetry), has been selected to explore the SID dissociation pattern of a complicated stacked ring protein complex. SID produces both α and β subunits while collision induced dissociation (CID) produces only highly charged α subunit. In addition, the charge reduced 20S proteasome produces the α7β7 fragment, reflecting the stacked ring topology of the complex. The combination of SID and charge reduction is shown to be a powerful tool for the study of protein complex structure.

Ring VCO Design with Variable Capacitance XNOR Delay Cell

This paper presents the new designs of voltage controlled oscillator (VCO) with three transistors XNOR gate as variable capacitive load. Design of three, five and seven stage VCO have been reported using single ended ring topology. CMOS inverter based delay cell is modified with addition of XNOR capacitive load. Output frequency has been controlled by applied voltage to variable capacitive load. Control voltage of VCO has been varied from 1.3 to 2.1 V. Three stage VCO provides output frequency variation in the range of 3.52–3.34 GHz with power consumption variation from 0.81 to 1.76 mW. Five stage VCO shows frequency variation from 2.06 to 1.98 GHz with power consumption varying from 1.35 to 2.94 mW. Moreover, frequency of seven stage VCO varies from 1.47 to 1.41 GHz with varying power from 1.89 to 4.12 mW. Power consumption and output frequency of proposed VCO circuits have been compared with earlier reported circuits and present approach shows considerable improvements.

P2P Resource Sharing in Wired/Wireless Mixed Networks

This paper presents a new routing protocol called Manager-based Routing Protocol (MBRP) for sharing resources in wired/wireless mixed networks. MBRP specifies a manager node for a designated sub-network (called as a group), in which all nodes have the similar connection properties; then all manager nodes are employed to construct the backbone overlay network with ring topology. The manager nodes act as the proxies between the internal nodes in the group and the external world, that is not only for centralized management of all nodes to a certain extent, but also for avoiding the messages flooding in the whole network. The experimental results show that compared with Gnutella2, which uses super-peers to perform similar management work, the proposed MBRP has less lookup overhead including lookup latency and lookup hop count in the most of cases. Besides, the experiments also indicate that MBRP has well configurability and good scaling properties. In a word, MBRP has less transmission cost of the shared file data, and the latency for locating the sharing resources can be reduced to a great extent in the wired/wireless mixed networks.

An efficient energy hole alleviating algorithm for wireless sensor networks

Many consumer products in the home environment are managed by the Wireless Sensor Networks (WSNs). However, the energy hole problem in the WSNs which with logical ring topology and uniformly distributed sensors is usually caused by the energy exhaustion of the sensors which distributed in the first radius range of the sink. This paper firstly analyzed the energy consumption model of the sensor, the data transmission model of the sensor, and the energy consumption distribution model of the WSNs. Then, a WSN Energy Hole Alleviating (WSNEHA) algorithm, which is based on the data forwarding and router selection strategy, is proposed. The WSNEHPA adopts the data forwarding and routing selection strategy to balance the energy consumption of the sensors in the first radius range of the sink. Experimental results demonstrate that WSNEHPA can efficiently balance the energy consumption of the sensors in the first radius range of the sink, and that the lifetime of the WSNs can be extended efficiently.