Improving the yield of NoC-based systems through fault diagnosis and adaptive routing

We propose an effective and low cost method to increase the yield and the lifetime of torus NoCs. The method consists in detecting and diagnosing NoC interconnect faults using BIST structures and activating alternative paths for the faulty links. Alternative paths use the inherent redundancy of the torus topology, thus leading to minimal performance, area, and power overhead. We assume an extended interconnect fault model comprising stuck-at and pairwise shorts within a single link or between any two links in the network. Experimental results for a 3×3 NoC show that the proposed approach can correctly diagnose 93% of all possible interconnect faults and can mitigate 42% of those faults (representing 94.4% of the solvable faults) with a worst case performance penalty of 8% and 1% of area overhead. We also demonstrate the scalability of the method by presenting its application to larger NoCs.     

A comprehensive quality model for service-oriented systems

In a service-oriented system, a quality (or Quality of Service) model is used (i) by service requesters to specify the expected quality levels of service delivery; (ii) by service providers to advertise quality levels that their services achieve; and (iii) by service composers when selecting among alternative services those that are to participate in a service composition. Expressive quality models are needed to let requesters specify quality expectations, providers advertise service qualities, and composers finely compare alternative services. Having observed many similarities between various quality models proposed in the literature, we review these and integrate them into a single quality model, called QVDP. We highlight the need for integration of priority and dependency information within any quality model for services and propose precise submodels for doing so. Our intention is for the proposed model to serve as a reference point for further developments in quality models for service-oriented systems. To this aim, we extend the part of the UML metamodel specialized for Quality of Service with QVDP concepts unavailable in UML.

User Activities Outliers Detection; Integration of Statistical and Computational Intelligence Techniques

In this article, a hybrid technique for user activities outliers detection is introduced. The hybrid technique consists of a two‐stage integration of principal component analysis and fuzzy rule‐based systems. In the first stage, the Hamming distance is used to measure the differences between different activities. Principal component analysis is then applied to the distance measures to find two indices of Hotelling's T² and squared prediction error. In the second stage of the process, the calculated indices are provided as inputs to the fuzzy rule‐based systems to model them heuristically. The model is used to identify the outliers and classify them. The proposed system is tested in real home environments, equipped with appropriate sensory devices, to identify outliers in the activities of daily living of the user. Three case studies are reported to demonstrate the effectiveness of the proposed system. The proposed system successfully identifies the outliers in activities distinguishing between the normal and abnormal behavioral patterns.     

The shaping of information by visual metaphors

The nature of an information visualization can be considered to lie in the visual metaphors it uses to structure information. The process of understanding a visualization therefore involves an interaction between these external visual metaphors and the user's internal knowledge representations. To investigate this claim, we conducted an experiment to test the effects of visual metaphor and verbal metaphor on the understanding of tree visualizations. Participants answered simple data comprehension questions while viewing either a treemap or a node-link diagram. Questions were worded to reflect a verbal metaphor that was either compatible or incompatible with the visualization a participant was using. The results suggest that the visual metaphor indeed affects how a user derives information from a visualization. Additionally, we found that the degree to which a user is affected by the metaphor is strongly correlated with the user's ability to answer task questions correctly. These findings are a first step towards illuminating how visual metaphors shape user understanding, and have significant implications for the evaluation, application, and theory of visualization.     

An exploratory study of the accessibility of state government Web sites

This paper focuses on Web accessibility. Relevant legislation and judicial decisions are reviewed, and prior empirical research is presented. This study presents the results from the Web accessibility analysis of the home pages of the 50 states and the District of Columbia. It found that twenty-nine percent of the home pages do not meet the requirements for Conformance Level A Web accessibility. Only one state meets Conformance Level AA standards, which are the minimum standards recommended for Web accessibility, and no state meets Conformance Level AAA standards. This paper also discusses how to address common accessibility problems.

Chemical mediation of egg capsule deposition by mud snails

Mud snails (Ilyanassa obsoleta = Nassarius obsoletus = Nassa obsoleta) deposit eggs in protective capsules on hard substrata in soft bottom environments. We studied sites of egg capsule deposition and snail movement responses to odors to determine if chemoreception plays a role in deposition site selection. From results of field surveys, laboratory experiments, and field experiments, we conclude that mud snails use chemoreception for capsule deposition. Attractive odors originate from mud snail and whelk egg capsules and from living bivalves. Evidence for attractive odors from conspecifics is equivocal. Capsules are deposited on living odor sources and nearby hard substrates. We hypothesize that deposition of capsules on living substrates increases the likelihood that embryos will survive by decreasing the chance of smothering of embryos by sediments.     

Granularity in reciprocity

Witnessing in merging biological, social and algorithmic realities is crucial to trust, as modelled in the YUTPA framework. Being witness and bearing witness is fundamental to human interaction. System participation in human communities of practice challenges the notion of witnessing and therefore the ability to build trust. Nevertheless, through trial and error, people in a variety of practices have found ways to establish the presence and develop trust in merging realities. This paper presents the results of 20 in-depth interviews with professionals from a variety of disciplines and nations. The conclusion of cumulative analysis is that systems do not witness themselves, but their output deeply affects the mental maps that human beings make of each other, the world around them and their own self. Essential qualities human beings seek when being involved with other beings are defined by granularity and reciprocity in the design of time (duration of engagement, synchronizing performance, integrating rhythms and moments to signify), place (body sense, material interaction, emotional space and situated agency), relation (shared meaning, engagement, reputation and use) and action (tuning, reciprocity, negotiation and quality of deeds). By designing granular interaction in 4 dimensions, reciprocity in witnessing obtains significance and the basis for establishing trust in a variety of presences emerges while human agency acquires potential.     

A multi-start iterated local search with tabu list and path relinking for the two-echelon location-routing problem

The two-echelon location-routing problem (LRP-2E) is raised by the design of transportation networks with two types of trips: first-level trips serving from one main depot a set of satellite depots, to be located, and second-level trips supplying customers from these satellites. In the proposed multi-start iterated local search (MS-ILS), three greedy randomized heuristics are used cyclically to get initial solutions. Each ILS run alternates between two search spaces: LRP-2E solutions, and travelling salesman (TSP) tours covering the main depot and the customers. The number of iterations allotted to a run is reduced whenever a known solution (stored in a tabu list) is revisited. MS-ILS can be reinforced by a path-relinking procedure (PR), used internally for intensification, as post-optimization, or both. On two sets with 24 and 30 LRP-2E instances, MS-ILS outperforms on average two GRASP algorithms and adding PR brings a further improvement. Our metaheuristic also surpasses a tabu search on 30 instances for a more general problem with several main depots. It is still effective on a particular case, the capacitated location-routing problem (CLRP): In a comparison with four published metaheuristics, only one (LRGTS, Prins et al., 2007) does better.     

Effect of automatic image realignment on visuomotor coordination in simulated laparoscopic surgery

During laparoscopic surgery, the surgeon's hand-eye coordination is often disrupted by the incongruent mapping between the orientation of the endoscopic view and the actual operative field. Two experiments were conducted to examine the effect of automatic image realignment on the performance of laparoscopic surgery. The first experiment investigated how visual-motor misalignment impacted laparoscopic surgery performance. Novice subjects were randomly assigned to one of the two paired viewing conditions in a simulated laparoscopic surgery environment: 1) the endoscope was either at the center of the modeled workspace with an optical axis of 90°, or at -45° from the midline of the subjects with an optical axis 45°; 2) the endoscope was either at 0°, or at 180° from the midline of the subjects, both with an optical axis of 45°. Each group of twelve subjects performed a dynamic point-and-touch task under the assigned pair of viewing conditions, each with eight image orientations, in a repeated-measures mixed design. The second experiment examined whether the automatic realigning mechanism that was activated mid-task (such that a congruent mapping between display and control was re-established if the mapping at the beginning of the task had been misaligned) was helpful to improve performance. Twelve novice subjects performed the same task as in the first experiment in a repeated-measures design. Performance was examined under three misaligned visuomotor mappings, each followed by the realigned mapping activated by the automatic realigning mechanism. Results showed that performance was best when the endoscopic image was perfectly aligned with the actual task space (0° image orientation), but degraded progressively as a function of deviation from perfect alignment. Subjects' performance maintained a consistent pattern across 8 image orientations regardless of optical axis orientation and endoscope location. Performance was improved with the automatic realigning mechanism. It is recommended that any solution to restore the visuomotor congruency in laparoscopic surgery should first align the image with the task space. This work has implications for the design of visualization systems in laparoscopic surgery.     

Minimum variance prediction and control for adaptive optics

Adaptive Optics (AO) systems enable to compensate the adverse effects of atmospheric turbulence on ground-based telescopes’ images in real time, using a deformable mirror (DM) inserted in the telescope’s optical path, and measurements provided by a wavefront sensor (WFS). This paper revisits minimum-variance (MV) control design for astronomical AO systems in a state-space framework. It presents a survey of the modeling and control issues arising in this multi-variable disturbance rejection problem. In a linear time-invariant framework, and under some mild assumptions, the optimal solution to MV control for AO systems is shown to be a discrete-time LQG controller. This result holds for a DM with instantaneous response, and for a fairly general class of DM’s dynamics. The state-space approach is extended to Wide-field Adaptive Optics (WfAO) configurations involving several DMs and/or WFSs. Integral-action control used in existing AO systems is compared with the LQG controller. Experimental WfAO results obtained on a laboratory test bench are presented, showing significant improvement in performance. Finally, open issues and perspectives of applicative and/or theoretical interests are discussed.