On absolute (robust) stability: slope restrictions andstability multipliers

Absolute stability for systems with several sector‐restricted and slope‐restricted nonlinearities is studied in this paper. A critical analysis of the multipliers is performed and the multipliers of Yakubovich type are chosen because the stability inequality is obtained with a minimum of technical assumptions. The main part of the paper is devoted to obtaining the Yakubovich‐type criterion in the unified context of stable, critical, and unstable cases for the linear part. The paper is motivated by the problem of pilot in‐the‐loop oscillations of the aircrafts where critical and unstable cases appear and the saturation nonlinearity is both sector and slope restricted. The paper contains some applications of the frequency domain inequalities. The conclusions show a ‘parsimony principle’: using as few free parameters as possible to obtain the largest possible domain of stability. The paper ends with conclusions and hints for further development. Copyright © 2011 John Wiley & Sons, Ltd.     

Density Displays for Data Stream Monitoring

In many business applications, large data workloads such as sales figures or process performance measures need to be monitored in real‐time. The data analysts want to catch problems in flight to reveal the root cause of anomalies. Immediate actions need to be taken before the problems become too expensive or consume too many resources. In the meantime, analysts need to have the “big picture” of what the information is about. In this paper, we derive and analyze two real‐time visualization techniques for managing density displays: (1) circular overlay d isplays which visualize large volumes of data without data shift movements after the display is full, thus freeing the analyst from adjusting the mental picture of the data after each data shift; and (2) variable resolution density displays which allow users to get the entire view without cluttering. We evaluate these techniques with respect to a number of evaluation measures, such as constancy of the display and usage of display space, and compare them to conventional d isplays with periodic shifts. Our real time data monitoring system also provides advanced interactions such as a local root cause analysis for further exploration. The applications using a number of real‐world data sets show the wide applicability and usefulness of our ideas.     

Exploiting User Interests to Characterize Navigational Patterns in Web Browsing Assistance

In order to be capable of exploiting context for pro-active information recommendation, agents need to extract and understand user activities based on their knowledge of the user interests. In this paper, we propose a novel approach for context-aware recommendation in browsing assistants based on the integration of user profiles, navigational patterns and contextual elements. In this approach, user profiles built using an unsupervised Web page clustering algorithm are used to characterize user ongoing activities and behavior patterns. Experimental evidence show that using longer-term interests to explain active browsing goals user assistance is effectively enhanced.

Multimodal focus attention and stress detection and feedback in an augmented driver simulator

This paper presents a driver simulator, which takes into account the information about the user’s state of mind (level of attention, fatigue state, stress state). The user’s state of mind analysis is based on video data and biological signals. Facial movements such as eyes blinking, yawning, head rotations, etc., are detected on video data: they are used in order to evaluate the fatigue and the attention level of the driver. The user’s electrocardiogram and galvanic skin response are recorded and analyzed in order to evaluate the stress level of the driver. A driver simulator software is modified so that the system is able to appropriately react to these critical situations of fatigue and stress: some audio and visual messages are sent to the driver, wheel vibrations are generated and the driver is supposed to react to the alert messages. A multi-threaded system is proposed to support multi-messages sent by the different modalities. Strategies for data fusion and fission are also provided. Some of these components are integrated within the first prototype of OpenInterface: the multimodal similar platform.     

Fibroblast protein profile analysis highlights the role of oxidative stress and vitamin K recycling in the pathogenesis of pseudoxanthoma elasticum

Pseudoxanthoma elasticum (PXE) is a genetic disorder associated to mutations in the ABCC6 gene; however, the pathogenetic mechanisms leading to elastic fibre calcifications and to clinical manifestations are still unknown. Dermal fibroblasts, directly involved in the production of the extracellular milieu, have been isolated from healthy subjects and from patients affected by PXE, cultured in vitro and characterized for their ability to produce reactive oxygen species, for structural and functional properties of their cell membranes, for changes in their protein profile. Data demonstrate that oxidative stress has profound and endurable consequences on PXE fibroblast phenotype being responsible for: reduced levels of global DNA methylation, increased amount of carbonylated proteins and of lipid peroxidation products, altered structural properties of cell membranes, modified protein expression. Data shed new light on the pathogenetic pathways in PXE, by identifying a network of proteins affecting elastic fibre calcification through inefficient vitamin K recycling, and highlight the role of differentially expressed proteins as targets for validating the efficacy of future therapeutic strategies aiming to delay and/or revert the pathologic phenotype of PXE fibroblasts. Moreover, data open new perspectives for investigating PXE-like phenotypes in the absence of ABCC6 mutations.     

A Soft,Fast and Versatile Electrohydraulic Gripper with Capacitive Object Size Detection

Soft robotic grippers achieve increased versatility and reduced complexity through intelligence embodied in their flexible and conformal structures. The most widely used soft grippers are pneumatically driven; they are simple and effective but require bulky air compressors that limit their application space and external sensors or computationally expensive vision systems for pick verification. In this study, a multi-material architecture for self-sensing electrohydraulic bending actuators is presented that enables a new class of highly versatile and reconfigurable soft grippers that are electrically driven and feature capacitive pick verification and object size detection. These electrohydraulic grippers are fast (step input results in finger closure in 50 ms), draw low power (6.5 mW per finger to hold grasp), and can pick a wide variety of objects with simple binary electrical control. Integrated high-voltage driving electronics are presented that greatly increase the application space of the grippers and make them readily compatible with commercially available robotic arms.     

Sub‐Micron Polymeric Stomatocytes as Promising Templates for Confined Crystallization and Diffraction Experiments

The possibility of using sub‐micrometer polymeric stomatocytes is investigated to effectuate confined crystallization of inorganic compounds. These bowl‐shaped polymeric compartments facilitate confined crystallization while their glassy surfaces provide their crystalline cargos with convenient shielding from the electron beam's harsh effects during transmission electron microscopy experiments. Stomatocytes host the growth of a single nanocrystal per nanocavity, and the electron diffraction experiments reveal that their glassy membranes do not interfere with the diffraction patterns obtained from their crystalline cargos. Therefore, it is expected that the encapsulation and crystallization within these compartments can be considered as a promising template (nanovials) that hold and protect nanocrystals and protein clusters from the direct radiation damage before data acquisition, while they are examined by modern crystallography methodologies such as serial femtosecond crystallography.