Search results for " networks"

Acoustic characterization of Silica aerogel clamped plates for perfect absorption purpose

2017

International audience; Silica aerogel has been widely studied as bulk material for its extremely low density and thermal conductivity. Plates or membranes made of this extremely soft materials exhibits interesting properties for sound absorption. A novel signal processing method for the characterization of an acoustic metamaterial made of silica aerogel clamped plates is presented. The acoustic impedance of a silica aerogel clamped plate is derived from the elastic theory for the flexural waves, while the transfer matrix method is used to model reflection and transmission coefficients of a single plate. Experimental results are obtained by using an acoustic impedance tube. The difference b…

OH-related Infrared Absorption Bands in Oxide Glasses

2005

We report the infrared activity, in the spectral region of the OH stretching modes, of different composite silicate glasses whose chemical composition is established by X-ray fluorescence measurements. The analysis of the absorption line profiles is made in terms of different spectral contributions, Gaussian in shape. The comparison with analogous spectra obtained in vitreous silica samples with impurity concentrations < 100 part per million moles is evidence of the effects of the different oxides on the vibrational properties of the OH groups. In particular, for oxide glasses a red shift of the composite band at about 3670 cm(-1), assigned to the OH stretching modes of free Si-OH groups an…

Proportional and Preemption-Enabled Traffic Offloading for IP Flow Mobility: Algorithms and Performance Evaluation

2018

IP Flow Mobility (IFOM) enables a user equipment to offload data traffic at the IP flow level. Although the procedure of IFOM-based flow offloading has been specified by 3GPP, how many IP flows should be offloaded and when offloading should be performed are not defined. Consequently, IP flows may be routed to a target access network which has a strong signal strength but with backhaul congestion or insufficient access capability. In this paper, we propose two algorithms, referred to as proportional offloading (PO), and proportional and preemption-enabled offloading (PPO), respectively, for IP flow offloading in hybrid cellular and wireless local area networks. The PO algorithm decides an op…

A Metaheuristic Bandwidth Allocation Scheme for FiWi Networks Using Ant Colony Optimization

2015

Optical-wireless access networks constitute a quite attractive solution to meet the ever-increasing bandwidth requirements of end-users, offering significant benefits such as ubiquitous coverage in the wireless domain and huge bandwidth in the optical domain. However, converging optical and wireless networking technologies, with Passive Optical Networks (PONs) and 4G wireless standards, such as the Worldwide Interoperability for Microwave Access (WiMAX) and the Long Term Evolution (LTE), entails major challenges that need to be addressed. In this context, designing an efficient and fair bandwidth distribution with Quality of Service (QoS) support is a difficult task due to the interdependen…

Metabolic shift of polyphosphate-accumulating organisms with different levels of polyphosphate storage

2012

Previous studies have shown that polyphosphate-accumulating organisms (PAOs) are able to behave as glycogen-accumulating organisms (GAOs) under different conditions. In this study we investigated the behavior of a culture enriched with Accumulibacter at different levels of polyphosphate (poly-P) storage. The results of stoichiometric ratios Gly degraded/HAc uptake, PHB synthesized/HAc uptake, PHV synthesized/HAc uptake and P release/HAc uptake confirmed a metabolic shift from PAO metabolism to GAO metabolism: PAOs with high poly-P content used the poly-P to obtain adenosine tri-phosphate (ATP), and glycogen (Gly) to obtain nicotinamide adenine dinucleotide (NADH) and some ATP. In a test whe…

Dropping out of school as a meaningful action for adolescents with social, emotional and behavioural difficulties

2013

This study examines and discusses dropping out of school related to adolescents with social, emotional and behavioural difficulties (SEBD). It is based on in-depth interviews of 10 adolescents between the ages of 16 and 20, three girls and two boys with internalised problems, and two girls and three boys with extroverted behavioural problems. Given this group of students' challenges at school, the aim of this paper is to explore the narratives of this adolescent group as they relate to the significance they attach to their dropout behaviour. An additional objective is to draw attention to what these findings are likely to mean for implementing preventive practices in school. Results show th…

Interference and Communications among Active Network Applications

1999

A New Adaptive Neural Harmonic Compensator for Inverter Fed Distributed Generation

2004

This paper deals with the command of inverters in DG (distributed generation) systems by use of linear neural networks in such a way that, with a slight upgrade of their control software, they can be used also to compensate for the harmonic distortion in the node where they are connected (local compensation), that is in the in the point of common coupling (PCC). To this purpose a neural estimator based on linear neurons (ADALINEs) has been developed which is able to act as a selective noise cancellers for each harmonic of the node voltage. The use of linear neurons permits the drawbacks of classical neural networks to be overcome and moreover the neural estimator is easy to implement, thus …

Is the nonREM–REM sleep cycle reset by forced awakenings from REM sleep?

2002

In selective REM sleep deprivation (SRSD), the occurrence of stage REM is repeatedly interrupted by short awakenings. Typically, the interventions aggregate in clusters resembling the REM episodes in undisturbed sleep. This salient phenomenon can easily be explained if the nonREM–REM sleep process is continued during the periods of forced wakefulness. However, earlier studies have alternatively suggested that awakenings from sleep might rather discontinue and reset the ultradian process. Theoretically, the two explanations predict a different distribution of REM episode duration. We evaluated 117 SRSD treatment nights recorded from 14 depressive inpatients receiving low dosages of Trimipram…

A conceptual model of feedback mechanisms in adjusted affordances – Insights from usage of a mental mobile health application

2023

Affordance theory provides one of the most prominent lenses through which the socio-technical aspects of a system’s use can be investigated and understood. In this context, the literature has proposed that perceived and actualized affordances may be adjusted over time. Yet, how the adjustment of affordances occurs has not been explained in detail. Thus, in this article, we develop a conceptual model of feedback mechanisms that includes a more explicit description of how affordances are perceived by users, whether actualized and adjusted. With the model, we introduce the central concept of a generative base, out of which affordance perceptions emerge and which can be updated through affordan…