We study first-order mean-field quantum phase transitions, in particular the exponentially fast closure of the energy gap with the system size. We consider exactly solvable ferromagnetic models and discuss their relation to the Grover problem to which they reduce in a particular limit. We compute the coefficient in the exponential closure of the gap using an instantonic approach. We also discus...

This communication reports for the first time the charging of a commercially available mobile phone, using Microbial Fuel Cells (MFCs) fed with real neat urine. The membrane-less MFCs were made out of ceramic material and employed plain carbon based electrodes.

Target coverage problem in wireless sensor networks is concerned with maximizing the lifetime of the network while continuously monitoring a set of targets. A sensor covers targets which are within the sensing range. For a set of sensors and a set of targets, the sensor-target coverage relationship is assumed to be known. A sensor cover is a set of sensors that covers all the targets. The targe...

monitoring the effective parameters of drying crops is necessary to evaluate and determine system performance under real conditions. hence, a monitoring system was constructed to determine the performance of a vegetation forced-convection solar dryer. digital temperature sensors were set up in the air inlet and outlet of the collector and the air outlet of the drying chamber. a program was writ...

We study the modulational instability in discrete lattices and we show how the discreteness drastically modifies the stability condition. Analytical and numerical results are in very good agreement. We predict also the evolution of a linear wave in the presence of noise and we show that modulational instability is the first step towards energy localization. PACS numbers: 6310, 0340K, 4610, 0545

Spiliopoulos, V. 2016. Improving Energy-Efficiency of Multicores using First-Order Modeling. Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1404. 52 pp. Uppsala: Acta Universitatis Upsaliensis. ISBN 978-91-554-9652-4. In the recent decades, power consumption has evolved to one of the most critical resources in a computer system. In the form o...

Wireless sensor networks (WSNs) consists of large number of spatially distributed autonomous sensor nodes. The sensor nodes have limited energy resources, processing and storage capabilities. Clustering is an energy efficient and scalable way to organize the WSN. Clustering algorithm is often adopted in wireless sensor networks but many clustering algorithm do not provide the required energy ef...

Abstract New methods are presented for microscopically characterizing defects in materials in terms of local energy and stress fields calculated at the firstprinciples level of theory. These fields provide a quantitative measure of the local disturbance created by defect-induced electronic and atomic inhomogeneities in a solid. The local stress density σαβ(r) is computed by explicitly evaluatin...

In this study, the energy loss near edge structure (ELNES) of carbon atoms in chair and tricycle conformers of hydrogenated graphene, namely 'graphane', has been calculated in the density functional theory using FP-LAPW method, and then, it has been compared with that of graphite and graphene. Using ELNES from chair conformer, the carbon K-edge was found to have a few main features including el...