Playing MUSIC — building context‐aware and self‐adaptive mobile applications

Although the idea of context‐awareness was introduced almost two decades ago, few mobile software applications are available today that can sense and adapt to their run‐time environment. The development of context‐aware and self‐adaptive applications is complex and few developers have experience in this area. On the basis of several demonstrators built by the joint European research project MUSIC, this paper describes typical context and adaptation features relevant for the development of context‐aware and self‐adaptive mobile applications. We explain how the demonstrators were realised using the open‐source platform MUSIC and present the feedback of the developers of these demonstrators. The main contribution of this paper is to show how the development complexity of context‐aware and self‐adaptive mobile applications can be mastered by using an adaptation framework such as MUSIC. Copyright © 2012 John Wiley & Sons, Ltd.     

Optimizing a remotely sensed proxy for plankton biomass in Lake Kivu

Many regions of the world, including inland lakes, present with suboptimal conditions for the remotely sensed retrieval of optical signals, thus challenging the limits of available satellite data-processing tools, such as atmospheric correction models (ACM) and water constituent-retrieval (WCR) algorithms. Working in such regions, however, can improve our understanding of remote-sensing tools and their applicability in new contexts, in addition to potentially offering useful information about aquatic ecology. Here, we assess and compare 32 combinations of two ACMs, two WCRs, and three binary categories of data quality standards to optimize a remotely sensed proxy of plankton biomass in Lake Kivu. Each parameter set is compared against the available ground-truth match-ups using Spearman’s right-tailed ρ. Focusing on the best sets from each ACM–WCR combination, their performances are discussed with regard to data distribution, sample size, spatial completeness, and seasonality. The results of this study may be of interest both for ecological studies on Lake Kivu and for epidemiological studies of disease, such as cholera, the dynamics of which has been associated with plankton biomass in other regions of the world.     

The generalised discrete algebraic Riccati equation in linear-quadratic optimal control

This paper investigates the properties of the solutions of the generalised discrete algebraic Riccati equation arising from the classic infinite-horizon linear quadratic (LQ) control problem. In particular, a geometric analysis is used to study the relationship existing between the solutions of the generalised Riccati equation and the output-nulling subspaces of the underlying system and the corresponding reachability subspaces. This analysis reveals the presence of a subspace that plays an important role in the solution of the related optimal control problem, which is reflected in the generalised eigenstructure of the corresponding extended symplectic pencil. In establishing the main results of this paper, several ancillary problems on the discrete Lyapunov equation and spectral factorisation are also addressed and solved.     

Analytical and graphical design of lead–lag compensators

In this article an approach based on inversion formulae is used for the design of lead–lag compensators which satisfy frequency domain specifications on phase margin, gain margin and phase (or gain) crossover frequency. An analytical and graphical procedure for the compensator design on the Nyquist and Nichols planes is presented with some numerical examples.     

A design methodology for high-order class-D audio amplifiers

This paper presents a design methodology for high-order class-D amplifiers, based on their similarity with sigma–delta ( $\Upsigma\Updelta$ ) modulators, for which established theory and toolboxes are available. The proposed methodology, which covers the entire design flow, from specifications to component sizing, is validated with three design examples, namely a second-order, a third-order, and a fourth-order class-D amplifier. Moreover, the third-order class-D amplifier has been integrated on silicon and characterized, further confirming the validity of the whole design flow. The achieved results demonstrate that high-order class-D amplifiers can achieve total-harmonic-distortion (THD) performance compatible with the specifications of high-end audio applications (THD  ≈ 90 dB), which would be unfeasible with conventional first-order class-D amplifiers.     

Mucociliary clearance and respiratory function in foundry workers

The aim of the study was to establish whether changes occur in respiratory function, particularly mucociliary clearance, among second fusion smeltery workers. The research covered 93 male smelters employed in steel forming and casting and 116 male workers of an electric power station, considered as non-exposed. Physiological, pathological and occupational histories of all subjects under study were available. An ECCS respiratory symptoms questionnaire was administered to all subjects ad the two groups also underwent a general medical examination, a spirometry and a chest X-ray. During the medical examination sputum was collected from the subjects to measure mucus transport rate on frog palate, expressed as Normalised Frog Palate Transport Rate (NFPTR). For the environmental research, dust, fumes and gas samplings were taken either at a fixed station or by means of personal dosimeters. Environmental research revealed very low concentrations of respiratory irritants (total dust: 0.2-6.8 mg/m3; respirable dust: 0.1-4.9 mg/m3; total silica: < 2-15.5%; respirable silica: < 0.004-0.3 mg/m3; iron: 0.008-0.085 mg/m3; chromium and manganese: < 0.001 mg/m3; fumes and gases: well below the TLV. The two groups were homogeneous with regard to age and smoking habits. Exposed workers showed rales, dyspnoea and spontaneous phlegm more frequently than non-exposed workers. NFPTR alterations were checked in 49 out of 81 exposed and in 18 out of 81 non-exposed subjects (chi squared = 22.9; p < 0.001). Stratification of the results according to smoking habits further confirmed the strong association between occupational exposure and NFPTR alterations. Smelters showed significantly lower mean NFPTR values compared to non-exposed subjects; also, the mean value of NFPTR in the exposed was below 0.70, which is considered the lowest individual limit in normal subjects. The only variable which explains a large part of the variability of NFPTR is past work in a smeltery rather than in an electric power station. The spirometries showed that only the mean PEF values were significantly lower among the exposed. Stratified analysis of the results according to smoking habits in the two groups revealed a close association between smeltery work and reduction of PEF to under 80% of the ECCS 1983 theoretical values, independently of smoking habits. We also compared the mean PEF values, both as measured values and as percent values of the ECCS 1983 theoretical values, stratified for occupational exposure and smoking; the results again showed that differences between these mean values were mainly due to current or past work in the foundry.(ABSTRACT TRUNCATED AT 400 WORDS)     

Genetic algorithm to design logical topologies in reconfigurable WDM networks

A new method to design logical topologies based on genetic algorithms is presented. Not only does the algorithm determine which nodes should be connected by means of lightpaths with the aim of minimizing congestion, but it also solves the routing and wavelength assignment problem. In this way, the algorithm guarantees that the logical topology obtained can be embedded in the optical network subject to the available set of resources. The algorithm is effective in terms of both congestion and fairness. For instance, when compared with other work, the congestion is significantly reduced (from 20% to 75% depending on the matrix of traffic considered), and the fairness, when evaluated in terms of the Jain index, is generally higher than 0.94. Moreover, the algorithm brings advantages when employed in dynamic scenarios where the logical topology is frequently reconfigured, as it is fast and, in contrast to other algorithms previously proposed, the calculation process can be stopped at any time (if required) in order to give the best virtual topology found up to the moment.

Kinematic viscosity studies of the binary ethane- 1,2-diol/ n,n-dimethylformamide solvent system at various temperatures

Kinematic viscosity data (ν) are presented for ethane-1,2-diol, for N, N-dimethylformamide and for nine binary mixtures in the - 10°C to 80°C temperature range. The experimental data were fitted by several empirical relations such as Grunberg-Nissan (1949), McAllister (1960), Heric (1966), Lobe (1973), Auslander (1964) and polynomial equations. Some considerations regarding the meaning of the obtained adjustment parameters are made. Furthermore, a new best fit equation is proposed and its validity has been compared to that of the other relations on the basis of the reproducibility of the experimental data.