Optimal curing policy for epidemic spreading over a community network with heterogeneous population

The design of an efficient curing policy, able to stem an epidemic process at an affordable cost, has to account for the structure of the population contact network supporting the contagious process. Thus, we tackle the problem of allocating recovery resources among the population, at the lowest cost possible to prevent the epidemic from persisting indefinitely in the network. Specifically, we analyze a susceptible-infected-susceptible epidemic process spreading over a weighted graph, by means of a first-order mean-field approximation. First, we describe the influence of the contact network on the dynamics of the epidemics among a heterogeneous population, that is possibly divided into communities. For the case of a community network, our investigation relies on the graph-theoretical notion of equitable partition; we show that the epidemic threshold, a key measure of the network robustness against epidemic spreading, can be determined using a lower-dimensional dynamical system. Exploiting the computation of the epidemic threshold, we determine a cost-optimal curing policy by solving a convex minimization problem, which possesses a reduced dimension in the case of a community network. Lastly, we consider a two-level optimal curing problem, for which an algorithm is designed with a polynomial time complexity in the network size.Comment: to be published on Journal of Complex Network

Interplay between disorder and intersubband collective excitations in the two-dimensional electron gas

Intersubband absorption in modulation-doped quantum wells is usually appropriately described as a collective excitation of the confined two-dimensional electron gas. At sufficiently low electron density and low temperatures, however, the in-plane disorder potential is able to damp the collective modes by mixing the intersubband charge-density excitation with single-particle localized modes. Here we show experimental evidence of this transition. The results are analyzed within the framework of the density functional theory and highlight the impact of the interplay between disorder and the collective response of the two-dimensional electron gas in semiconductor heterostructures.Comment: 5 pages, 4 figures, RevTeX. Accepted for publication in Phys. Rev. B (Rapid. Comm.

Human posture tracking and classification through stereo vision and 3D model matching

The ability of detecting human postures is particularly important in several fields like ambient intelligence, surveillance, elderly care, and human-machine interaction. This problem has been studied in recent years in the computer vision community, but the proposed solutions still suffer from some limitations due to the difficulty of dealing with complex scenes (e.g., occlusions, different view points, etc.). In this article, we present a system for posture tracking and classification based on a stereo vision sensor. The system provides both a robust way to segment and track people in the scene and 3D information about tracked people. The proposed method is based on matching 3D data with a 3D human body model. Relevant points in the model are then tracked over time with temporal filters and a classification method based on hidden Markov models is used to recognize principal postures. Experimental results show the effectiveness of the system in determining human postures with different orientations of the people with respect to the stereo sensor, in presence of partial occlusions and under different environmental conditions

Sustainable combined production of hydrogen and energy from biomass in malaysia

This work relates to a comparison between process solutions for the production of H2 and the coproduction of H2 and energy by means of a zero emission biomass integrated gasification and a combined cycle (BIGCC) power plant. The energy production is 10 MWe, in agreement with the Small Renewable Energy Power Plant (SREP) Program, promoted by the Government of Malaysia. H2 is obtained by supercritical water gasification (SCWG), a technology of interest for the processing of biomass with high moisture content. An economic analysis has been carried out in order to demonstrate the feasibility of the process solutions and to compare their convenience. The feedstock is 280,000 t/y of Empty Fruit Bunch (EFB), a biomass obtained in the Palm Oil Industry. The location of the site is Teluk Intak District in the State of Perak (Malaysia). The processes are designed with Aspen Plus® V7.2. The aim of this work is to develop detailed process flow diagrams for the supercritical water gasification technology in order to study and compare the convenience and the sustainability of different scenarios that can be adopted in an industrial context. The processes have been developed to reach zero emissions and zero wastes. CO2 and solid residuals are recycled inside the palm oil lifecycle. A cost analysis has been performed to find out the convenience of the proposed solutions

Soft Magnetorotons and Broken-Symmetry States in Bilayer Quantum Hall Ferromagnets

The recent report on the observation of soft magnetorotons in the dispersion of charge-density excitations across the tunneling gap in coupled bilayers at total Landau level filling factor $\nu_T=1$ is reviewed. The inelastic light scattering experiments take advantage of the breakdown of wave-vector conservation that occurs under resonant excitation. The results offer evidence that in the quantum Hall state there is a roton that softens and sharpens markedly when the phase boundary for transitions to highly-correlated compressible states is approached. These findings are interpreted with Hartree-Fock evaluations of the dynamic structure factor. The model includes the effect of disorder in the breakdown of wave-vector conservation and resonance enhancement profiles within a phenomenological approach. These results link the softening of magnetorotons to enhanced excitonic Coulomb interactions in the ferromagnetic bilayers.Comment: 6 pages, 5 figures; conference: EP2DS-1

Inter-edge strong-to-weak scattering evolution at a constriction in the fractional quantum Hall regime

Gate-voltage control of inter-edge tunneling at a split-gate constriction in the fractional quantum Hall regime is reported. Quantitative agreement with the behavior predicted for out-of-equilibrium quasiparticle transport between chiral Luttinger liquids is shown at low temperatures at specific values of the backscattering strength. When the latter is lowered by changing the gate voltage the zero-bias peak of the tunneling conductance evolves into a minimum and a non-linear quasihole-like characteristic emerges. Our analysis emphasizes the role of the local filling factor in the split-gate constriction region.Comment: 4 pages, 4 figure

A Power Cap Oriented Time Warp Architecture

Controlling power usage has become a core objective in modern computing platforms. In this article we present an innovative Time Warp architecture oriented to efficiently run parallel simulations under a power cap. Our architectural organization considers power usage as a foundational design principle, as opposed to classical power-unaware Time Warp design. We provide early experimental results showing the potential of our proposal

DETERMINATION OF THE FOREST ROAD NETWORK INFLUENCE ON THE SUPPLY CHAIN FOR FIREWOOD PRODUCTION BY DISCRETE EVENT SIMULATION

In this study a Discrete-event simulation (D-es) has been developed to analyze the wood supply chain for firewood production in a mountain area in North-eastern Italy. The D-es is applied in the modeling of extraction (Full Tree System), processing of roundwood into wood assortments (cross-cut and sorting), offroad and on-road transport. In order to estimate the productivity functions and parameters, field studies were conducted to gather data about the different operations linked in the model. Also a GIS network analysis was developed to integrate the spatial information onthe covered distance to the D-es model for each of the supposed Scenarios. The results indicats that an increment of 5 m ha-1 of the forest road network could significantly increase the productivity of the wood supply chain up to 2%

Spatial multi-criteria decision process to define maintenance priorities of forest road network: an application in the Italian Alpine region

The combination of GIS tools and Analytic Hierarchy Process (AHP) techniques is used to develop a Decision Support System to rank the maintenance priorities of a forest road network according to the actual conditions and needs. The decision-making process is divided into 4 stages. The first stage fixes the objectives of the analysis as the minimization of the sediment production from road surface and the maximization of the social value of the road. The second stage defines the hierarchical structure of the decision problem. At this stage the set of factors (criteria) to maximize each objective and the evaluation methods are defined. At the third stage AHP analysis is applied using a specific application running on ArcGIS, to calculate the evaluation layer that represents the importance of each road according to the set objectives. The values of the evaluation layer are used at the fourth stage to rank the maintenance interventions according to the given benefit. The methodology has been tested in a forest road network with an extension of 107.8 km including in the analysis the real budget constraints and maintenance costs. The results show that the integrated use of GIS and AHP analysis represents a valuable tool to rate the importance of the forest road network for the management of a mountain territory and to define priorities among maintenance operations of the road network, in order to maximize the overall benefit with limited economic resource

Energy analysis of different municipal sewage sludge-derived biogas upgrading techniques

Biomass-derived energy sources are rising their importance since both public opinion and legislation are currently calling for a sustainable development. Biogas is an energy source which can come from municipal sewage sludge digestion thus coupling the advantages of being a renewable energy source and of allowing a smart waste reutilization. In order to fully exploit the biogas potential as vehicle fuel or natural gas substitute, biogas itself must be treated in order to obtain biomethane. Biogas upgrading, i.e., the treatment for CO2 removal, can be performed by several techniques, each one characterised by a different energy demand. Since no clear guidelines are given in literature for choosing among different biogas upgrading processes, this work presents a quantitative analysis, from an energy view point, of water scrubbing, MEA (monoethanolamine) scrubbing, and MDEA (methyldiethanolamine) scrubbing when applied to obtain biomethane from municipal sewage sludge-derived biogas. Heat and electrical power consumptions of each of the above mentioned processes have been obtained by means of process simulation with commercial packages (such as Aspen Plus®). The aim of the work is the energetic comparison among these different techniques. Such a comparison can help in assessing the impact of the biogas purification step on the energy balance of the whole biomethane production process