A Level Set Model for Image Classification

We present a supervised classification model based on a variational approach. This model is devoted to find an optimal partition composed of homogeneous classes with regular interfaces. The originality of the proposed approach concerns the definition of a partition by the use of level sets. Each set of regions and boundaries associated to a class is defined by a unique level set function. We use as many level sets as different classes and all these level sets are moving together thanks to forces which interact in order to get an optimal partition. We show how these forces can be defined through the minimization of a unique fonctional. The coupled Partial Differential Equations (PDE) related to the minimization of the functional are considered through a dynamical scheme. Given an initial interface set (zero level set), the different terms of the PDE's are governing the motion of interfaces such that, at convergence, we get an optimal partition as defined above. Each interface is guided by internal forces (regularity of the interface), and external ones (data term, no vacuum, no regions overlapping). Several experiments were conducted on both synthetic and real images.     

Bulk synthesis of carbon nanostructures: Hollow stacked-cone-helices by chemical vapor deposition

Bulk synthesis of hollow carbon stacked-cone-helices of diameter from 10 nm to 0.5 μm is reported. The fibres’ walls are made up of parallel stacked-cone-like structures with an inter-cone distance from 3.38 to 3.5 Å. Apex angles observed are in the range from 30° to 110°, suggesting that the carbon nanofibres are constructed by a single graphene sheet which forms a helical structure instead of a stacked cone or open stacked cup structure. A new 3-D construction of the stacked-cone-helix is presented. Our results show that metal Pd catalyst plays a key role in obtaining carbon products with cone-helix structure and high yield (200%). These novel fibres could be used as nano-wire templates, micro-spray, and field emitters.     

A taxonomy of task-based parallel programming technologies for high-performance computing

Task-based programming models for shared memory—such as Cilk Plus and OpenMP 3—are well established and documented. However, with the increase in parallel, many-core, and heterogeneous systems, a number of research-driven projects have developed more diversified task-based support, employing various programming and runtime features. Unfortunately, despite the fact that dozens of different task-based systems exist today and are actively used for parallel and high-performance computing (HPC), no comprehensive overview or classification of task-based technologies for HPC exists. In this paper, we provide an initial task-focused taxonomy for HPC technologies, which covers both programming interfaces and runtime mechanisms. We demonstrate the usefulness of our taxonomy by classifying state-of-the-art task-based environments in use today.     

Location and orientation of panel on the screen as a structural visual element to highlight text displayed

Searching for information on the internet has become a daily activity. It is considered to be a complex cognitive activity that involves visual attention. Many studies have demonstrated that users’ information search are affected both by the spatial configuration of words and the elements displayed on the screen: elements that are used to structure web pages. One of these elements, the web panel, contains information. Web panel is a rectangular area with a colored background that was used to highlighting content presented in this specific rectangular area. Our general hypothesis was that the presence of a panel on a web page would affect the structure of a word display, as a result, information search accuracy. We carried out an experiment in which we manipulated the presence vs. the absence of a panel, as well as its orientation on the screen (vertical vs. horizontal). Twenty participants were asked to answer questions while their eye movements were recorded. Results showed that the presence of a panel resulted in reduced accuracy and shorter response times. Panel orientation affected scanpaths, especially when they were orientated vertically. We discuss these findings and suggest ways in which this research could be developed further in future.     

Grid Deployment Experiences: Grid Interoperation

Over recent years a number of Grid projects have emerged which have built Grid infrastructures that are now the computing backbones for various user communities. A significant number of these communities are limited to one Grid Infrastructure due to the different middleware and operations procedures used. Grid Interoperation is trying to bridge these differences and enable Virtual Organizations to access resources independent of the Grid project affiliation. Building upon the experiences the authors have gained while working on interoperation between EGEE and various other Grid infrastructures as well as through co-chairing the Grid Interoperation Now (GIN) efforts of the Open Grid Forum (OGF), this paper gives an overview of Grid Interoperation and describes various methods that can be used to connect Grid Infrastructures. The case is made for standardization in key areas and why the Grid community should move more aggressively towards standards.     

Disruptions in Spatial Networks: a Comparative Study of Major Shocks Affecting Ports and Shipping Patterns

Networks and Spatial Economics - In this research, the effect of local exogenous shocks on seaports and maritime networks is assessed throughout three case-studies. The Hanshin-Awaji earthquake,...     

A quadratic edge-finding filtering algorithm for cumulative resource constraints

The cumulative scheduling constraint, which enforces the sharing of a finite resource by several tasks, is widely used in constraint-based scheduling applications. Propagation of the cumulative constraint can be performed by several different filtering algorithms, often used in combination. One of the most important and successful of these filtering algorithms is edge-finding. Recent work by Vilím has resulted in a ?? (kn log n) algorithm for cumulative edge-finding (where n is the number of tasks and k is the number of distinct capacity requirements), as well as a new related filter, timetable edge-finding, with a complexity of ??(n ²). We present a sound ??(n ²) filtering algorithm for standard cumulative edge-finding, orthogonal to the work of Vilím; we also show how this algorithm’s filtering may be improved by incorporating some reasoning from extended edge-finding, with no increase in complexity. The complexity of the new algorithm does not strictly dominate previous edge-finders for small k, and it sometimes requires more iterations to reach the same fixpoint; nevertheless, results from Project Scheduling Problem Library benchmarks show that in practice this algorithm consistently outperforms earlier edge-finding filters, and remains competitive with timetable edge-finding, despite the latter algorithm’s generally stronger filtering.     

Mechanisms and parameters controlling the tricalcium aluminate reactivity in the presence of gypsum

To understand the mechanisms and the parameters controlling the reactivity of tricalcium aluminate in the presence of gypsum at an early age, a study of the hydration of the “C₃A-sulphate” system by isothermal microcalorimetry, conductimetry and a monitoring of the ionic concentrations of diluted system suspensions have been carried out with various gypsum quantities. The role of C₃A source and its fineness were also studied. This work shows the fast initial formation of AFm phase followed by ettringite formation during the period when the sulphate is consumed. It has been highlighted that the time necessary to consume all the gypsum varies with the type of C₃A and it has been attributed to the intrinsic reactivity of each one and mainly to the change of fineness from one C₃A to another. Results are discussed alongside hypothesis from the literature to explain the slowing down of C₃A hydration process in the presence of calcium sulphate.