Search results for " network topolog"
showing 7 items of 7 documents
Efficient techniques for energy saving in data center networks
2018
Data centers are constructed with a huge number of network devices to support the expanding cloud based services. These devices are used to achieve the highest performance in case of full utilization of the network. However, the peak capacity of the network is rarely reached. Consequently, many devices are set into idle state and cause a huge energy waste leading to a non-proportionality between the network load and the energy consumed. In this paper, we propose a new approach to improve the efficiency of data centers in terms of energy consumption. Our approach exploits the correlation in time of the inter-node communication traffic and some topological features to maximize energy saving w…
Algorithms for Graph and Network Analysis: Clustering and Search of Motifs in Graphs
2019
In this article we deal with problems that involve the analysis of topology in graphs modeling biological networks. In particular, we consider two important problems: (i) Network clustering, aiming at finding compact subgraphs inside the input graph in order to isolate molecular complexes, and (ii) searching for motifs, i.e., sub-structures repeated in the input network and presenting high significance (e.g., in terms of their frequency). We provide a compact overview of the main techniques proposed in the literature to solve these problems.
Relations between structure and estimators in networks of dynamical systems
2011
The article main focus is on the identification of a graphical model from time series data associated with different interconnected entities. The time series are modeled as realizations of stochastic processes (representing nodes of a graph) linked together via transfer functions (representing the edges of the graph). Both the cases of non-causal and causal links are considered. By using only the measurements of the node outputs and without assuming any prior knowledge of the network topology, a method is provided to estimate the graph connectivity. In particular, it is proven that the method determines links to be present only between a node and its “kins”, where kins of a node consist of …
The linear saturated decentralized strategy for constrained flow control is asymptotically optimal
2013
We present an algorithm for constrained network flow control in the presence of an unknown demand. Our algorithm is decentralized in the sense that it is implemented by a team of agents, each controlling just the flow on a single arc of the network based only on the buffer levels at the nodes at the extremes of the arc, while ignoring the actions of other agents and the network topology. We prove that our algorithm is also stabilizing and steady-state optimal. Specifically, we show that it asymptotically produces the minimum-norm flow. We finally generalize our algorithm to networks with a linear dynamics and we prove that certain least-square optimality properties still hold.
Diversity and complexity of microbial communities from a chlor-alkali tailings dump
2015
Abstract Revegetation of the tailings dumps produced by various industrial activities is necessary to prevent dust storms and erosion and represents a great challenge for ecological restoration. Little is known about the microbial colonisation and community structure of revegetated tailings following site exploitation. Here, we report the sequencing of 16S rRNA and internal transcribed spacer (ITS) fungal RNA gene amplicons from chlor-alkali residue and from an adjacent undisturbed soil to define the composition and assembly of the rhizosphere microbial communities. After quality filtering, a total of 72,373 and 89,929 bacterial sequences and 122,618 and 111,209 fungal sequences remained fo…
Synthetic approach to the design of wide-band microwave injection-locked amplifiers
2010
In this work, a synthesis-based approach to the realization of wide-band microwave injection-locked amplifiers (ILA) is proposed. To this purpose, a transmission-type topology is combined with a feedback structure in which the "core ILA" is intentionally separated from the output (power) amplifier. A modular, matched, design of individual building blocks of the core ILA is then adopted, which allows their first-approximation exact modeling in the dynamical complex-envelope domain, following the theory earlier developed by Calandra-Sommariva. On this basis, analytic expressions for the main operating characteristics of the ILA (such as the locking bandwidth under small signal operation) are …
Approach to the Design of Transmission-Type Injection-Locked Microwave Oscillators through Behavioral Block Modeling
2010
In this work, an attempt is made toward the development of a systematic design method for the performance- driven dimensioning of the various elements comprising the structure of modern transistor-based microwave injection- locked oscillators with transmission-type topologies (TILOs). The proposed approach is based on the use of appropriate diakoptics of the various circuit blocks into a matched environment, and their behavioral modeling in the fundamental- frequency dynamical complex envelope domain with the help of standard circuit and E.M. simulation CAD tools. This will permit, in the end, to obtain closed-form expressions for the main TILO performances in terms of the design parameters…