On-line maximum-order induced hereditary subgraph problems

We first study the competitive ratio for the on‐line version of the problem of finding a maximum‐order induced subgraph satisfying some hereditary property, under the hypothesis that the input graph is revealed by clusters. Next, we focus ourselves on two of the most known instantiations of this problem: the maximum independent set and the maximum clique. Finally, we study a variant of the on‐line maximum‐weight induced hereditary subgraph problem. Our results can also be seen as general reductions, either from off‐line problems to the corresponding on‐line versions, or between on‐line problems. The concept of reduction was absent, until now, from the on‐line computation.     

Environmental impacts of the infrastructure for district heating in urban neighbourhoods

District heating is a technology for distributing centrally produced heat for space heating and sanitary hot-water generation for residential and commercial uses. The objectives are to identify which subsystems and components of a district heating grid are the main contributors to the overall impact of the infrastructure; and provide environmentally oriented design strategies for the future eco-redesign of these kinds of infrastructures. This paper performs a life-cycle assessment (LCA) to determine the environmental impacts of a district heating infrastructure in an urban neighbourhood context. The analysis covers seven subsystems (power plant, main grid, auxiliary components of the main grid, trench works, service pipes, buildings and dwellings) and twelve standard components. The results for the subsystems show that the sources of impact are not particularly located in the main grid (less than 7.1% contribution in all impact categories), which is the focus of attention in the literature, but in the power plants and dwelling components. These two subsystems together contribute from 40% to 92% to the overall impact depending on the impact categories. Concerning the components, only a reduced number are responsible for the majority of the environmental impact. This facilitates identifying effective strategies for the redesign of the infrastructure.     

The greatest allowed relative error in weights and threshold of strict separating systems.

An important consideration when applying neural networks is the sensitivity to weights and threshold in strict separating systems representing a linearly separable function. Perturbations may affect weights and threshold so that it is important to estimate the maximal percentage error in weights and threshold, which may be allowed without altering the linearly separable function. In this paper, we provide the greatest allowed bound which can be associated to every strict separating system representing a linearly separable function. The proposed bound improves the tolerance that Hu obtained. Furthermore, it is the greatest bound for any strict separating system. This is the reason why we call it the greatest tolerance.     

A drain current model for Schottky-barrier CNT-FETs

We present here a physics-based drain current model for Schottky-barrier carbon nanotube field-effect transistors. The model captures a number of features exhibited by these transistors such as thermionic and tunnel emission, ambipolar conduction, ballistic transport, multimode propagation and electrostatics dominated by the nanotube capacitance     

Single crystal growth of organic photoconductors: phthalocyanine

An effective method of growing single crystals of organic photoconductors such as phthalocyanine in the presence of doping impurity such as iodine by vacuum sublimation is discussed in this paper. This method is very useful especially when an organic material does not have a melting point but decomposes above a particular temperature. So far, doping has been done by exposing the previously grown organic single crystals to the dopant vapour, but growing the crystal in the presence of dopant vapour makes the doped-crystal more efficient and stable. The photosensitivity as well as the photoconductivity of the doped crystals by this method increases significantly.     

Simple and Efficient Translation from LTL Formulas to Büchi Automata

We present a collection of simple on-the-fly techniques to generate small Büchi automata from Linear Time Logic formulas. These techniques mainly involve syntactic characterizations of formulas, and yet allow efficient computations. Thus heavily relying on such proof-theoretic issues, we can omit the classical formula pre-simplification step, and also simulation-based post-simplification steps (aka model-theoretic issues).Although closely related to other similar recent works in the same topic, our ideas have led to an implementation that performs significantly better than some of the best available tools, such as Wring or LTL2BA. We compare our tool BAOM (“Büchi Automata Once More”) with others, on formulas commonly found in the literature, and on randomly generated testbenchs.     

A macroscopic model for species transport during in vitro tissue growth obtained by the volume averaging method

In this work, we study the possibility of deriving a macroscopic model to describe reaction and transport by diffusion and convection of two species within a porous medium as encountered during in vitro tissue growth. The starting point is a boundary value problem of diffusion-advection and reaction in a three-phase system, the two species being identified as the nutrient for cell growth and the metabolic product within the framework of tissue culture. The method of volume averaging is applied to the set of microscopic equations. Under the local mass equilibrium assumption and a series of constraints on the parameters of the system that are identified, one obtains a one-equation macroscopic model corresponding to a dispersion-reaction equation. Associated closure problems allowing the computation of effective coefficients that appear in this macroscopic model are provided.     

Analysis of convective momentum and wall heat transfer: application to vortex boundary layer interaction

The main topic of this paper is the analysis of momentum and heat transfer mechanisms occurring inside a disturbed boundary layer. This analysis is carried out based on a phenomenological decomposition using von Karman’s integral equations, in which appear terms that account for several contributions: the flat plate term, and the unsteady and external gradient terms.This method is applied to the interaction between a single transverse vortex and a boundary layer developing on a flat plate. Based on numerical simulations, we present a qualitative and quantitative study of the behavior of momentum and heat wall transfer described by the terms resulting from the phenomenological decomposition. Finally, the time-dependent behavior of the analogy factor is investigated.     

Natural variation of toxicity in encrusting spongeCrambe crambe (Schmidt) in relation to size and environment

The presence of intraspecific variation in toxicity and its relationship with biological or ecological factors were studied in the spongeCrambe crambe. Within-specimen (periphery and central part), between-size (<1000 mm² in area, between 1000 and 10,000 mm² and >10,000 mm²) and between-habitat (well-illuminated and dark communities) variations in toxicity were evaluated by the Microtox bioassay. Quantitative differences were detected that were not attributable to within-specimen variation but to size and habitat effects. Habitat comparisons showed that sponges in the shaded habitat were significantly more toxic than those of the well-illuminated community. Sponges of the smaller size classes displayed significantly less toxicity than the medium-sized specimens. Results are interpreted under the optimal defense theory and their ecological implications are considered.