Hybrid Nodes Research Articles

Hybrid Placement of Internet Gateways and Rechargeable Routers with Guaranteed QoS for Green Wireless Mesh Networks

To solve the challenges of ever-increasing energy consumption, wireless mesh networks (WMNs) consisting of routers using renewable energy sources have been emerging as a promising solution. In this paper, we jointly consider the node placement and energy management in a hybrid WMN consisting of electricity-powered Internet gateways and solar-powered rechargeable routers. We introduce a new metric of failure rate to evaluate network performance and formulate the problem as a constrained optimization problem with the objective of minimizing both capital expenses on installation and operational expenses related to energy consumption. The network Quality of Service (QoS) requirements include meeting the failure rate requirement, the users' dynamic traffic demand requirements in both downlink and uplink, the gateways' and routers' capacity constraints, the maximal transmission power constraints, and the rechargeable routers' energy consumption constraints. Furthermore, we propose a minimum cost association algorithm to connect mesh clients to the Internet in different slots and a greedy placement algorithm to find approximate solutions for hybrid node placement. Simulation results show that the hybrid placement with rechargeable routers reveals its advantage for large scale networks in terms of more energy saving. Compared with the optimal placement achieved by the exhaustive search, our proposed algorithm can achieve good performance with the significantly reduced computation complexity.

Identification of hybrid node and link communities in complex networks.

Identifying communities in complex networks is an effective means for analyzing complex systems, with applications in diverse areas such as social science, engineering, biology and medicine. Finding communities of nodes and finding communities of links are two popular schemes for network analysis. These schemes, however, have inherent drawbacks and are inadequate to capture complex organizational structures in real networks. We introduce a new scheme and an effective approach for identifying complex mixture structures of node and link communities, called hybrid node-link communities. A central piece of our approach is a probabilistic model that accommodates node, link and hybrid node-link communities. Our extensive experiments on various real-world networks, including a large protein-protein interaction network and a large network of semantically associated words, illustrated that the scheme for hybrid communities is superior in revealing network characteristics. Moreover, the new approach outperformed the existing methods for finding node or link communities separately.

Accelerating dissipative particle dynamics simulations for soft matter systems

Abstract Dissipative particle dynamics (DPD) is a coarse-grained particle-based simulation method that offers microscopic-scale insights into soft matter systems. We present an efficient implementation of a DPD model for graphical processing units (GPUs). As implemented in the LAMMPS molecular dynamics package, it can run effectively on current-generation supercomputers which often have hybrid nodes containing multi-core CPUs and (one or more) GPUs. Using efficient communication of information between the CPUs and GPUs, DPD interactions can be computed on the GPU while other portions of a full simulation model (boundary conditions, constraints, bonded interactions, diagnostic calculations, etc.) can be performed on the CPU. Our GPU-enhanced runs show a speedup of up to 9.5× versus many-core CPU simulations, and can run scalably across thousands of compute nodes. We briefly discuss how the new GPU implementation was validated against the CPU version for thermodynamics, diffusion, and hydrodynamic behavior. We also highlight large-scale models which the faster DPD implementation has enabled, for studies of monolayer self-assembly and thin-film instabilities.

Energy-Efficient Soft-Input Soft-Output Signal Detector for Iterative MIMO Receivers

This paper presents the VLSI design of an energy-efficient, high-throughput soft-input soft-output signal detector for iterative multiple-input multiple-output (MIMO) receiver. The detector is evolved from our previously developed imbalanced fixed complexity sphere decoder and adopts several new algorithm-level techniques to exploit the available a priori information of transmitted bits. More specifically, an adaptive tree-travel control scheme, a reliability-dependent log-likelihood ratio correction method and an iteration-based hybrid node enumeration technique are proposed to provide near-optimal detection performance with much reduced computational complexity. A multi-stage parallel VLSI architecture is developed to implement the proposed algorithm with high detection throughput. Furthermore, the block-level clock gating is deployed to save power when the tree-search space is reduced, while still preserving the constant-throughput feature. As a proof of concept, we designed the iterative detector using a 65-nm CMOS technology and conducted post-layout simulation. The core area is 0.64 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> with 198.2 k gates. Working at 240-MHz clock frequency with 1.0-V voltage supply, the detector achieves a maximum 1.44-Gbps throughput. Under frequency-selective channels, the detector core consumes 98.5-, 127.9-, and 149.5-pJ energy per bit detection in open-loop, 2-iteration, and 4-iteration modes, respectively.

Between places and flows: towards a new agenda for neighbourhood research in an age of mobility

This article discusses the role of the neighbourhood in an era of increased mobility. It explores the consequences of the “new mobilities paradigm”, which argues that the growing importance of flows – of people, goods and information – results in a deterritorialization of social practices. Rows thus gain prominence in comparison to places like regions and neighbourhoods. At the same time, however, neighbourhoods continue to play a role in the actions and imaginations of people, neighbourhood organizations, and government policies. People still live in neighbourhoods, and governments still try to solve often severe social problems through neighbourhood policies. We argue that the neighbourhood has to be re‐imagined as a collection of hybrid nodes connecting a multiplicity of flows that bind actors and objects in order to understand the potential effectiveness of these policies. From this new mobilities perspective, we make suggestions for future neighbourhood research.

Мультиагентные методы и инструментальные средства управления в сервис - ориентированной распределенной вычислительной среде

The paper discusses the issues related to ensuring the effective scaling of the job flow generated by problem-oriented distributed computing systems in heterogeneous Grid with hybrid nodes. Considers the multiagent methods and tools of the new generation, to ensure effective management of the combined job flow of scalable service-oriented software systems and load balancing for computing resources of runtime environment. Describes a high-level tools for developing services of scalable software systems. A distinctive feature of the presented methods and tools is use of elements of the economic theory (such as elements of regulation of supply and demand of resources) in the coordinated multiagent management of cluster Grid with hybrid nodes, both at the Grid level, and at the application level. The functions of problem-oriented computing environment (user application) is realized in the form of Grid-services using technology Web Services Resource Framework and patterns of interaction with local resource managers of Grid nodes. To create the agent of application is used development environment High-performance computing Service-oriented Multiagent System Framework, developed by the authors. A number of scientific services for experimental Grid are given as examples of organization of the problem-oriented computing environment (user application) using methods and tools considered in this paper. The results of their effective functioning is analyzed.

A Hybrid Node Scheduling Approach Based on Energy Efficient Chain Routing for WSN

Energy efficiency is usually a significant goal in wireless sensor networks (WSNs). In this work, an energy efficient chain (EEC) data routing approach is first presented. The coverage and connectivity of WSNs are discussed based on EEC. A hybrid node scheduling approach is then proposed. It includes sleep scheduling for cyclically monitoring regions of interest in time-driven modes and wakeup scheduling for tracking emergency events in event-driven modes. A failure rate is introduced to the sleep scheduling to improve the reliability of the system. A wakeup sensor threshold and a sleep time threshold are introduced in the wakeup scheduling to reduce the consumption of energy to the possible extent. The results of the simulation show that the proposed algorithm can extend the effective lifetime of the network to twice that of PEAS. In addition, the proposed methods are computing efficient because they are very simple to implement.

A New Method to Solve Static Voltage Collapse Point with Hybrid Power Network Equations

Electric power network components can be simulated with equivalent circuit and establish the hybrid node voltage and branch current electricity network analysis model based on it. We form the equations reflected the voltage collapse conditions, and establish the extended power flow equations with the hybrid equations, the static voltage collapse point can be calculated by solving them. The advantage of this method is that the power flow calculation can be convergence smoothly near the collapse point because of the extended power flow equations when the Jacobian matrix tends to be singular. The convergence can be achievable just because the joining of the equation reflecting the voltage collapse conditions has changed the structure of the Jacobian matrix. The simulation results show that this method is very effective.

Electron Correlation in the Condensed Phase from a Resolution of Identity Approach Based on the Gaussian and Plane Waves Scheme.

The second-order Møller-Plesset perturbation energy (MP2) and the Random Phase Approximation (RPA) correlation energy are increasingly popular post-Kohn-Sham correlation methods. Here, a novel algorithm based on a hybrid Gaussian and Plane Waves (GPW) approach with the resolution-of-identity (RI) approximation is developed for MP2, scaled opposite-spin MP2 (SOS-MP2), and direct-RPA (dRPA) correlation energies of finite and extended system. The key feature of the method is that the three center electron repulsion integrals (μν|P) necessary for the RI approximation are computed by direct integration between the products of Gaussian basis functions μν and the electrostatic potential arising from the RI fitting densities P. The electrostatic potential is obtained in a plane waves basis set after solving the Poisson equation in Fourier space. This scheme is highly efficient for condensed phase systems and offers a particularly easy way for parallel implementation. The RI approximation allows to speed up the MP2 energy calculations by a factor 10 to 15 compared to the canonical implementation but still requires O(N(5)) operations. On the other hand, the combination of RI with a Laplace approach in SOS-MP2 and an imaginary frequency integration in dRPA reduces the computational effort to O(N(4)) in both cases. In addition to that, our implementations have low memory requirements and display excellent parallel scalability up to tens of thousands of processes. Furthermore, exploiting graphics processing units (GPU), a further speedup by a factor ∼2 is observed compared to the standard only CPU implementations. In this way, RI-MP2, RI-SOS-MP2, and RI-dRPA calculations for condensed phase systems containing hundreds of atoms and thousands of basis functions can be performed within minutes employing a few hundred hybrid nodes. In order to validate the presented methods, various molecular crystals have been employed as benchmark systems to assess the performance, while solid LiH has been used to study the convergence with respect to the basis set and system size in the case of RI-MP2 and RI-dRPA.

Seamlessly transformable hybrid packet and circuit switching for eff icient optical networks

Efforts in realizing all-optical packet switching are overwhelming in the past decade. While optical packet switching remains an attractive switching paradigm in the long run, technical challenges prohibit it from becoming a practical solution for the ever-growing bandwidth hunger during the next few years. Finding a technically viable way to meet the increasing capacity requirement with good scalability and flexibility becomes a clear pursue for the community. Hybrid packet and circuit switching is considered to be one promising technique in realizing high performance switching at low cost and less energy consumption, by taking the advantage of both packet switching and circuit switching. In this paper, we review existing work in hybrid optical packet and circuit switching. We discuss the key technical challenges in realizing hybrid optical packet and circuit switching. We further introduce our ongoing efforts in building a seamlessly transformable packet/circuit-switching node with hybrid optical and electronic components. We show that in a hybrid node, the scheduling complexity with typical scheduling algorithms may be reduced to half of a node running in full packet switching mode.

THE INFLUENCE OF WELDING DEFORMATION TYPES OF HYBRID NODE ON ASSEMBLY SUITABILITY

The article presents welding deformation types identified in a hybrid node. The hybrid node is a new structure element. Its implementation requires solving many problems, especially those related to the technology. The most important problems in this field are welding deformations arising at the prefabrication stage of a node fabrication. Welding deformations influence the quality of prefabricated section and cause an increase of manufacturing costs. Therefore, a definition of influence of each deformation type on assembly suitability is a significant problem. The expert method presented in the article makes it possible to define this influence.

A Novel Offline PLI-RWA and Hybrid Node Architecture for Zero Blocking and Time Delay Reduction in Translucent Optical WDM Networks

In this paper, we contrive a model that underpins the offline Physical Layer Impairment-Routing and Wavelength Assignment (PLI-RWA) issue in translucent networks. We introduce an innovative PLI-Signal Quality Aware RWA (PLI-SQARWA) algorithm that (a) guarantees zero blocking due to signal degradation and wavelength contention and (b) aims at minimizing the total required number of network components i.e. regenerators and all-optical wavelength converters (AOWCs). Further, in view of reducing the time delay due to optical-electrical-optical (OEO) conversions, we propose a novel electro-optical hybrid translucent node architecture. We show that PLI-SQARWA outperforms a recent heuristic for RWA and regenerator placement (RP) in terms of capital expenditure (CapEx) and time delay; while demonstrating superior blocking performance at all traffic loads. In addition, at high traffic loads, PLI-SQARWA also starts to provision savings on operational expenditure (OpEx). We proceed to the performance comparison of network equipped with the proposed hybrid node and existing translucent and transparent node architectures. The results clearly show that use of the hybrid node incurs less time delay at a similar blocking performance shown by nodes which use OEO conversion for both, regeneration and/or wavelength conversion. The results presented also highlight the significance of equipping the PLI-RWA routing phase with signal quality awareness in order to reduce the network component count and the use of AOWCs to minimize time delay due to OEO conversions.

Control and Operation to Hybrid Optical Network

In this paper, a novel hybrid optical network system is presented. The continuing increase of data traffic keeps the pressure on the backbone telecommunication networks requiring more diverse and more intelligent allocation of capacity. Optical networking has become a key technology in accommodating the rapidly expanding Internet traffic. Hybrid nodes are now playing a key role in optical networks by facilitating efficient traffic management. New optical networks are expected to support the increasing network load by employing both sophisticated transmission (wavelength division multiplexing division (WDM)) and switching technologies (optical switches and cross-connects). This study will explain how the hybrid nodes achieve with different network models and make it operation through innovative technical designs.

Combined Analysis of Cost and Traffic Grooming Policies for Hybrid Networks Under Dynamic Traffic Requests

The benefit of a two-layer hybrid IP/MPLS (multi-protocol label switching) over a wavelength division multiplexing network has been analyzed considering both the cost and different grooming policies. A detailed cost and performance analysis of hybrid networks is done for three different grooming policies. The hybrid network cost is compared with that of an opaque network for equal traffic demand and equal blocking probability of dynamic requests of label switched paths. An algorithm is given to design optimum hybrid nodes for different grooming policies to provide the desired blocking probability for a given number of dynamic connection requests. The results show that all three applied grooming policies (IP layer first, optical layer first, and one hop first) result in lower costs of the hybrid network architecture than for the opaque network. In addition, an adaptive one hop first method is given to improve the best of the applied grooming policies, which limits grooming in heavily loaded hybrid nodes to achieve load balancing. The simulation results show that the new policy significantly reduces the overall blocking probability.

AN MPI PERFORMANCE MONITORING INTERFACE FOR CELL BASED COMPUTE NODES

In this paper, we present a methodology for profiling parallel applications executing on the family of architectures commonly referred as the "Cell" processor. Specifically, we examine Cell-centric MPI programs on hybrid clusters containing multiple Opteron and IBM PowerXCell 8i processors per node such as those used in the petascale Roadrunner system. We analyze the performance of our approach on a PlayStation3 console based on Cell Broadband Engine—the CBE—as well as an IBM BladeCenter QS22 based on PowerXCell 8i. Our implementation incurs less than 0.5% overhead and 0.3 µs per profiler call for a typical molecular dynamics code on the Cell BE while efficiently utilizing the limited local store of the Cell's SPE cores. Our worst-case overhead analysis on the PowerXCell 8i costs 3.2 µs per profiler call while using only two 5 KiB buffers. We demonstrate the use of our profiler on a cluster of hybrid nodes running a suite of scientific applications. Our analyses of inter-SPE communication (across the entire cluster) and function call patterns provide valuable information that can be used to optimize application performance.

Embedding paths of variable lengths into hypercubes with conditional link-faults

Faults in a network may take various forms such as hardware failures while a node or a link stops functioning, software errors, or even missing of transmitted packets. In this paper, we study the link-fault-tolerant capability of an n-dimensional hypercube ( n-cube for short) with respect to path embedding of variable lengths in the range from the shortest to the longest. Let F be a set consisting of faulty links in a wounded n-cube Q n , in which every node is still incident to at least two fault-free links. Then we show that Q n - F has a path of any odd (resp. even) length in the range from the distance to 2 n - 1 (resp. 2 n - 2 ) between two arbitrary nodes even if | F | = 2 n - 5 . In order to tackle this problem, we also investigate the fault diameter of an n-cube with hybrid node and link faults.

Extended Newick: it is time for a standard representation of phylogenetic networks

BackgroundPhylogenetic trees resulting from molecular phylogenetic analysis are available in Newick format from specialized databases but when it comes to phylogenetic networks, which provide an explicit representation of reticulate evolutionary events such as recombination, hybridization or lateral gene transfer, the lack of a standard format for their representation has hindered the publication of explicit phylogenetic networks in the specialized literature and their incorporation in specialized databases. Two different proposals to represent phylogenetic networks exist: as a single Newick string (where each hybrid node is splitted once for each parent) or as a set of Newick strings (one for each hybrid node plus another one for the phylogenetic network).ResultsThe standard we advocate as extended Newick format describes a whole phylogenetic network with k hybrid nodes as a single Newick string with k repeated nodes, and this representation is unique once the phylogenetic network is drawn or the ordering among children nodes is fixed. The extended Newick format facilitates phylogenetic data sharing and exchange, and also allows for the practical use of phylogenetic networks in computer programs and scripts. This standard has been recently agreed upon by a number of computational biologists, is already supported by several phylogenetic tools, and avoids the different drawbacks of using an a priori unknown number of Newick strings without any additional mark-up to represent a phylogenetic network.ConclusionThe adoption of the extended Newick format as a standard for the representation of phylogenetic network is an important step towards the publication of explicit phylogenetic networks in peer-reviewed journals and their incorporation in a future database of published phylogenetic networks.

Research of P2P overlay in heteromerous network

Most of the existing overlays are designed for only one network. This paper analyses the characteristic of heteromerous network and proposes a tree structure overlay for it. We classify the nodes into two types: common node and hybrid node. We design new routing table and new algorithms for node (especially for hybrid node) joining, leaving and searching. The simulation result shows that the overlay is well suit for heteromerous network. The algorithm is convergent in large-scale situation.

A Visibility-Driven Approach for Zone Management in Simulations

Massively multi-user simulations aim to support a large number of users while keeping the communication among the parties synchronous and highly interactive. In this paper, we present a collaborative virtual architecture that supports a large number of users by dividing the virtual environment into multiple adjacent hexagonal regions in order to manage the interest of the entities. A master node, called a hybrid node, constructs a Peer-to-Peer (P2P) overlay network to connect and manage nodes that lie in its region. Messaging is done at the application layer rather than the network layer, and a node-joining algorithm is proposed to reflect the underlying network physical topology onto the data distribution pathways among the end hosts to enhance the system performance. In addition, the introduction of a buffer zone between adjacent zones reduces the number of connections and disconnections that occur when a node frequently moves at the boundary of the two zones and provides more resilience to the system. We also attempt to shift the messaging among parties in one region from a zone-based method to a visibility-driven method to refine their interest by enabling message filtering. The effectiveness of this collaboration architecture is tested through a prototype implementation and a high level application.

Fast algorithms for computing the tripartition-based distance between phylogenetic networks

Consider two phylogenetic networks $${\cal N}$$ and $${\cal N}$$ ’ of size n. The tripartition-based distance finds the proportion of tripartitions which are not shared by $${\cal N}$$ and $${\cal N}$$ ’. This distance is proposed by Moret et al. (2004) and is a generalization of Robinson-Foulds distance, which is orginally used to compare two phylogenetic trees. This paper gives an $$O(\min \{k n \log n, n \log n + hn\})$$ -time algorithm to compute this distance, where h is the number of hybrid nodes in $${\cal N}$$ and $${\cal N}$$ ’ while k is the maximum number of hybrid nodes among all biconnected components in $${\cal N}$$ and $${\cal N}$$ ’. Note that $k \ll h \ll n$ in a phylogenetic network. In addition, we propose algorithms for comparing galled-trees, which are an important, biological meaningful special case of phylogenetic network. We give an $O(n)$-time algorithm for comparing two galled-trees. We also give an $$O(n + kh)$$ -time algorithm for comparing a galled-tree with another general network, where h and k are the number of hybrid nodes in the latter network and its biggest biconnected component respectively.