Implementation of an LED backlight for avionics displays

Abstract— The replacement of conventional light sources used to backlight displays with LEDs is very attractive in avionics. Today's LED technology provides devices suitable to implement display backlight sources but specific requirements need to be satisfied for avionics displays. This paper covers the development of an innovative LED backlight dedicated to avionics displays, realized in a new box geometry in order to generate more than 10,000 cd/m² on a 6 × 5‐in. active area using less than 28 W of power.     

Energy cost and mechanical efficiency of riding a human-powered recumbent bicycle

When dealing with human-powered vehicles, it is important to quantify the capability of converting metabolic energy in useful mechanical work by measuring mechanical efficiency. In this study, net mechanical efficiency (eta) of riding a recumbent bicycle on flat terrain and at constant speeds (v, 5.1-10.0 m/s) was calculated dividing mechanical work (w, J/m) by the corresponding energy cost (C(c), J/m). w and C(c) increased linearly with the speed squared: w = 9.41 + 0.156 . v(2); C(c) = 39.40 + 0.563 . v(2). eta was equal to 0.257 +/- 0.0245, i.e. identical to that of concentric muscular contraction. Hence, i) eta seems unaffected by the biomechanical arrangement of the human-vehicle system; ii) the efficiency of transmission seems to be close to 100%, suggesting that the particular biomechanical arrangement does not impair the transformation of metabolic energy in mechanical work. When dealing with human-powered vehicles, it is important to quantify mechanical efficiency (eta) of locomotion. eta of riding a recumbent bicycle was calculated dividing the mechanical work to the corresponding energy cost of locomotion; it was practically identical to that of concentric muscular contraction (0.257 +/- 0.0245), suggesting that the power transmission from muscles to pedals is unaffected by the biomechanical arrangement of the vehicle.     

Towards personalized recommendation by two-step modified Apriori data mining algorithm

In this paper a new method towards automatic personalized recommendation based on the behavior of a single user in accordance with all other users in web-based information systems is introduced. The proposal applies a modified version of the well-known Apriori data mining algorithm to the log files of a web site (primarily, an e-commerce or an e-learning site) to help the users to the selection of the best user-tailored links. The paper mainly analyzes the process of discovering association rules in this kind of big repositories and of transforming them into user-adapted recommendations by the two-step modified Apriori technique, which may be described as follows. A first pass of the modified Apriori algorithm verifies the existence of association rules in order to obtain a new repository of transactions that reflect the observed rules. A second pass of the proposed Apriori mechanism aims in discovering the rules that are really inter-associated. This way the behavior of a user is not determined by “what he does” but by “how he does”. Furthermore, an efficient implementation has been performed to obtain results in real-time. As soon as a user closes his session in the web system, all data are recalculated to take the recent interaction into account for the next recommendations. Early results have shown that it is possible to run this model in web sites of medium size.     

Walking in the resonance with the COMAN robot with trajectories based on human kinematic motion primitives (kMPs)

Research in humanoid robotics aims to develop autonomous systems that are able to assist humans in the performance of everyday tasks. Part of the robotics community claims that the best solution to guarantee the maximum adaptability of robots to the majority of human tasks is mimicry. Based on this premise both the structure of the human body and human behavior have been the focus of studies, with the aim of imitating and reproducing on robotic systems the results of millennia of human evolution. The research presented in this paper aims (i) at transferring the features of human locomotion to the COmpliant huMANoid (COMAN) robot, by means of kinematic motion primitives (kMPs) extracted from human subjects, and (ii) at improving the energetic performance of the walk of COMAN by exploiting its intrinsic compliance: it will be shown that, when the robot is walking at a gait frequency that is close to one of the main resonance frequencies of the mechanism, the springs contribute to tracking the human-like kMPs-based trajectories imposed, providing at the right time about 15 % of the energy required for locomotion, and that was previously stored.     

Phytogrowth Properties of Limonoids Isolated from Cedrela ciliolata

An epimeric mixture of the limonoid photogedunin, isolated from the heartwood of C. ciliolata, as well as its R- and S-acetate derivative were evaluated for phytotoxicity in mono- and dicotyledoneous plants. A mixture of epimeric photogedunin 1 and 2, a mixture of epimeric photogedunin acetate, (R)-photogedunin acetate 3, and (S)-photogedunin acetate 4 inhibited seed germination, seedling growth, and root and hypocotyl/coleoptyle growth in all species assayed. The concentration of phytochemicals required for 50% inhibition ranged from 4.5 to 300 M. Inhibitory plant responses appeared to require that the OH-group at C-23 be acetylated in photogedunin, since the nonacetylated compound showed less phytotoxic activity.     

The New About News: How Print,Online, Free,and Mobile Coconstruct New Audiences in Italy,France, Spain,the UK,and Germany

This paper presents cross‐national research on news readership diversification. We compare written news (print and free newspapers, online and mobile news services) audiences in the 5 most populous and industrialized European countries (Italy, France, Spain, the UK and Germany). Outlining a sociodemographic portrait of these different news users is important in order to understand the changes undergone inside the world of written news. We draw on a telephone survey carried out in 2009, using a representative population sample (N=7,255). The survey considers sociodemographic variables, including a range of social activities and attitudinal variables, television, computer, and mobile phone ownership, and Internet access and use. Findings show a rich, but volatile relationship between written news, audience behaviors, and community participation.     

Triple dose of gadolinium-DTPA and delayed MRI in patients with benign multiple sclerosis

OBJECTIVES: To evaluate whether a triple dose of gadolinium-DTPA (Gd-DTPA) or delayed MRI increase the number, size, and conspicuousness of enhancing lesions in patients with benign multiple sclerosis. METHODS: T1 weighted brain MRI was carried out on 20 patients with benign multiple sclerosis (expanded disability status scale < 3 with a disease duration > 10 years) in two sessions. In the first session, one scan was obtained before and two scans five to seven minutes and 20-30 minutes after the injection of 0.1 mmol/kg Gd-DTPA (standard dose). In the second session, six to 24 hours later, the same procedure was repeated with 0.3 mmol/kg Gd-DTPA (triple dose). RESULTS: Nine enhancing lesions were found in seven patients (35%) using the standard dose of Gd-DTPA. The numbers of enhancing lesions increased to 13 (P = 0.03) and the number of patients with such lesions to eight (40%) on the delayed standard dose scans. On the early triple dose scans, we found 19 enhancing lesions in 10 patients (50%). The number of enhancing lesions was significantly higher (P = 0.01) than that obtained with the early standard dose. The number of enhancing lesions was 18 and the number of "active" patients 11 (55%) on the delayed triple dose scans. The enhancing areas increased progressively from the early standard dose scans to the delayed triple dose scans. The contrast ratios of the lesions detected in early standard dose scans was lower than those of lesions present in the early (P = 0.01) and delayed (P = 0.04) triple dose scans. CONCLUSIONS: More enhancing lesions were detected in patients with benign multiple sclerosis with both delay of MRI and the use of triple dose of Gd-DTPA suggesting that the amount of inflammation in the lesions of such patients is mild and heterogeneous.     

Relation between activation energy and induction in rubber sulfur vulcanization: An experimental study

The article presents the possibility to use the so-called frequency factors in order to select the optimal temperature to mix rubber blend recipes before vulcanization without inducing premature crosslinking. As secondary result of the research, it provides a very simple approach to evaluate induction assuming a first order kinetic approach. It has been frequently observed that the activation energy in a first order rubber vulcanization scheme appears to be function of the particular activators used and that activation energy links to the so-called waiting time (and induction) by means of the frequency factor through an exponential relationship. A total of 212 rheometer curves are experimentally obtained and suitably postprocessed, consisting of pure natural rubber (NR), polybutadiene (PB), and 50–50 or 70%–30% NR-PR blends in presence of different concentrations of sulfur and accelerants (diphenyl guanidine [DPG] and N-t-butylbenzothiazole-sulfenamide [TBBS]). Data reduction is carried out to have an insight into the most suitable temperature to utilize in the different cases in order to: (a) Obtain the best mixed blends without risking premature vulcanization and (b) design the induction phase without over vulcanize the blend and/or delaying curing because the time required is too long. Waiting time and induction are evaluated by means of a well-established exponential law requiring the knowledge of the activation energy (assuming for the sake of simplicity that crosslinking occurs following a first order reaction kinetic law) and a constant called “frequency factor”. Frequency factor, considering all reactions monomolecular for the sake of simplicity, is assumed of the order of magnitude of 10⁻¹³–10⁻¹⁴ s. All experimental data carried out are critically compared and a wide explanation of the expected induction times and most suitable temperatures to use in the mixing phase is provided in the different cases considered. The article provides a meaningful insight into the importance of the link existing among activation energy, vulcanization recipe (with particular regard to concentration of accelerants, blend between two rubbers with very different activation energies and interaction between two accelerants) and mixing temperature to adopt before curing.     

T c as a Function of Electron Doping in Mg10B2 Using Sc for Mg Substitution

We have studied the variation of superconducting critical temperature T _c as a function of electron doping in the Mg¹⁰B₂ system using Sc for Mg substitution. The critical temperature in the¹⁰B isotope substituted system Mg_{1? x} Sc _x ¹⁰B₂ increases by increasing the scandium content x in the range 0<x<0.012 up to 41.4 K, while the T _c of the natural boron system Mg_{1? x} Sc _x B₂ is nearly constant. The overall difference of T _c in Mg_{1? x} Sc _x B₂ as function of x between the natural B and ¹⁰B isotope system seems to indicate that the isotope effect shows large variations with electron doping as expected for the T _c enhancement driven by a shape resonance.