Power save-based adaptive multimedia delivery mechanism

The use of mobile computing devices has become more and more common as such devices have become more and more affordable and powerful. With increases in throughput speed and decreases in device size, wireless multimedia streaming to battery powered mobile devices has become widespread. However, the battery power has not kept up with the advances in technology and has not increased so rapidly. This deficiency in battery power provides motivation for development of more energy efficient multimedia streaming methods and procedures. As such, an adaptive delivery mechanism is proposed to take into account the various drains on battery life and adjust rates appropriately when the battery is low. This paper proposes a Power Save-based Adaptive Multimedia Delivery Mechanism (PS-AMy) which makes a seamless multimedia adaptation based on the current energy level and packet loss, in order to enable the multimedia streaming to last longer while maintaining acceptable user-perceived quality levels. The proposed mechanism is evaluated by simulation using Network Simulator (NS-2)

Preface to special issue (Fast reaction - slow diffusion scenarios: PDE approximations and free boundaries)

This issue is focussed on the modeling, analysis and simulation of fast reaction-slow transport scenarios as well as corresponding fast-reaction limits. Within this framework, internal sharp and thin reaction layers form and travel through the spatial domain often producing unexpected effects. Such situations appear in a variety of significant applications; for example flame propagation in combustion, segregation and aggregation of biological individuals, chemical attack on reactive porous materials (such as concrete or natural stone), dissolution and precipitation reactions in minerals, tumor growth, grain boundary motion, and temperature-induced phase transitions in shape-memory alloys represent typical cases in which the fast process is localized within a a priori unknown internal active layer

User quality of experience of mulsemedia applications

User Quality of Experience (QoE) is of fundamental importance in multimedia applications and has been extensively studied for decades. However, user QoE in the context of the emerging multiple-sensorial media (mulsemedia) services, which involve different media components than the traditional multimedia applications, have not been comprehensively studied. This article presents the results of subjective tests which have investigated user perception of mulsemedia content. In particular, the impact of intensity of certain mulsemedia components including haptic and airflow on user-perceived experience are studied. Results demonstrate that by making use of mulsemedia the overall user enjoyment levels increased by up to 77%

Modeling and simulation of phase-transitions in multicomponent aluminum alloy casting

The casting process of aluminum products involves the spatial distribution of alloying elements. It is essential that these elements are uniformly distributed in order to guarantee reliable and consistent products. This requires a good understanding of the main physical mechanisms that affect the solidification, in particular the thermodynamic description and its coupling to the transport processes of heat and mass that take place. The continuum modeling is reviewed and methods for handling the thermodynamics component of multi-element alloys are proposed. Savings in data-storage and computing costs on the order of 100 or more appear possible, when a combination of data-reduction and data-representation methods is used. To test the new approach a simplified model was proposed and shown to qualitatively capture the evolving solidification front

Detection of extended-spectrum β-lactamase and carbapenemase activity in Gram-negative bacilli using liquid chromatography - tandem mass spectrometry

PURPOSE: Several mass spectrometry-based methods for antimicrobial sensitivity testing have been described in recent years. They offer an alternative to commercially available testing systems which were considered to have disadvantages in terms of cost- and time-efficiency. The aim of this study was to develop a LC-MS/MS-based antibiotic hydrolysis assay for evaluating antimicrobial resistance of Gram-negative bacteria. METHODS: Four species of Gram-negative bacilli (Klebsiella pneumoniae, Escherichia coli, Providencia stuartii and Acinetobacter baumannii) were tested against six antibiotics from three different classes: ampicillin, meropenem, imipenem, ceftazidime, ceftriaxone and cefepime. Bacterial suspensions from each species were incubated with a mixture of the six antibiotics. Any remaining antibiotic following incubation were measured using LC-MS/MS. The results were interpreted using measurements obtained for an E. coli strain sensitive to all antibiotics and expressed as percentage of hydrolyzed antibiotic. These were subsequently compared to commercially-available system for the bacteria identification and susceptibility testing. RESULTS: Overall, LC-MS/MS assay and commercial antimicrobial susceptibility platform results showed good agreement in terms of an organism being resistant/sensitive to an antibiotic. The time required to complete the LC-MS/MS-based hydrolysis test was under 5 h, significantly shorter that commercially available susceptibility testing platforms. CONCLUSION: By using a sensitive strain for results interpretation and simultaneous use of multiple antibiotics, the proposed protocol offers improved robustness and multiplexing over previously described methods for antibiotic sensitivity testing. Nevertheless, further research is needed before routine assimilation of the method, especially for strains with intermediate resistance

The stability of the swirling flows with applications to hydraulic turbines

The presence of a large variety of vortex flows in nature and technology has raised many theoretical and numerical problems concerning the stability of such structures. In these conditions, in order to minimize the simulation requirements for nonlinear time-dependent problems, stability analyses of vortexmotions are of main importance in flow control problems. A particular case arises in the Francis turbines operate at partial discharge. The swirling flow downstream the runner becomes unstable inside the draft tube cone, with the development of a precessing helical vortex and associated severe pressure fluctuations [1]

Single and two-scale sharp-interface models for concrete carbonation—asymptotics and numerical approximation

We investigate the fast-reaction asymptotics for a one-dimensional reaction-diffusion system describing the penetration of the carbonation reaction in concrete. The technique of matched-asymptotics is used to show that the reaction-diffusion system leads to two distinct classes of sharp-interface models. These correspond to different scalings of a small parameter $\epsilon$ representing the fast-reaction and defined here as the ratio between the characteristic scale of diffusion for the fastest species and the characteristic scale of the carbonation reaction. We explore three conceptually different diffusion regimes in terms of the behavior of the effective diffusivities for the driving chemical species. The limiting models include one-phase and two-phase generalized Stefan moving-boundary problems as well as a nonstandard two-scale (micro-macro) moving-boundary problem---the main result of the paper. Numerical results, supporting the asymptotics, illustrate the behavior of the concentration profiles for relevant parameter regimes