Nitroxide-mediated polymerization of styrene initiated from the surface of fumed silica. Comparison of two synthetic routes

Nitroxide-mediated free radical polymerization of styrene was performed from 13 nm diameter fumed silica in two steps. First, an alkoxyamine, based on N-tert-butyl-N-(1-diethylphosphono-2,2-dimethylpropyl) nitroxide (DEPN) was covalently attached onto silica. Polystyrene chains with controlled molecular weights and narrow polydispersities were then grown from the alkoxyamine-functionalized nanoparticles surface in the presence of a ‘free’ sacrificial styrylDEPN alkoxyamine. Two strategies were investigated in order to immobilize the alkoxyamine initiator on the silica surface. In a first route, we synthesized a unimolecular alkoxyamine initiator carrying triethoxysilyl end groups reactive towards the silica surface. In a second route, the alkoxylamine was formed in situ by the simultaneous reaction of a polymerizable acryloxy propyl trimethoxysilane (APTMS), azobisisobutyronitrile (AIBN) and DEPN used as radical trap. In both cases, the grafting of both the initiator and the polystyrene chains was characterized and quantified by several techniques which allowed us to evaluate and compare the two strategies.     

Parlay‐based service provision in circuit‐ and packet‐switched telecommunications networks

The spectrum of potential value added services over Internet telephony is wide, but the current service provision solutions are inadequate or proprietary. The nature of Internet differs significantly from that of circuit switched network, however, VoIP architectures can capitalize service control architectures in the PSTN world. We describe such an architecture based on the intelligent network and the Parlay, employing distributed objects and mobile agents as enabling technologies. This architecture has been implemented in the PSTN and the Internet and it has provided a framework for service provisioning, augmenting the space of supported services. Copyright © 2004 John Wiley & Sons, Ltd.     

Stiffness properties and stiffness orientation distributions for various paper grades by non-contact laser ultrasonics

The stiffness properties, especially flexural rigidity (FR), out of plane shear rigidity (SR), and stiffness orientation distributions (SOD) are characterized for various paper grades, by a laser ultrasonics instrument. Laser ultrasonics generation is achieved through thermal dilatation by point focusing of a pulsed laser beam onto the surface of the specimen. By probing the excited broadband ultrasound propagating in the samples, the velocities dispersions are obtained and the materials properties are extracted. The measured FR and SR along machine direction (MD) and cross direction (CD) are presented for 10 paper samples ranging from thin copy papers to heavy linerboards. The SOD polar diagrams for some of the samples are also presented and discussed. The relationships of FR, SR, Young's and shear moduli with basis weight are discussed. It is observed that both the Young's and shear moduli tend to decrease significantly when the basis weight increases, going from copy paper to linerboard grades. We also found that SR reaches a maximum value and then decreases when the basis weight increases to 150 g/m² and above. This unusual behavior of SR can be explained by the noticeable reduction of shear modulus for heavy linerboards.     

Minimal schedulability interval for real-time systems of periodic tasks with offsets

We consider real-time systems in highly safety context where tasks have to meet strict deadlines. Tasks are periodic, may have offsets, share critical resources and be precedence constrained. Off-line scheduling should be of great help for such systems, but methods proposed in the literature cannot deal with them. Our aim is to extend and improve the well-known cyclicity result of Leung and Merill to every scheduling algorithm and to systems of interacting tasks with offsets. One of the main benefit of our result is to enable the use of off-line scheduling methods for those real-time critical systems.     

Bayesian Robot Programming

We propose a new method to program robots based on Bayesian inference and learning. It is called BRP for Bayesian Robot Programming. The capacities of this programming method are demonstrated through a succession of increasingly complex experiments. Starting from the learning of simple reactive behaviors, we present instances of behavior combination, sensor fusion, hierarchical behavior composition, situation recognition and temporal sequencing. This series of experiments comprises the steps in the incremental development of a complex robot program. The advantages and drawbacks of BRP are discussed along with these different experiments and summed up as a conclusion. These different robotics programs may be seen as an illustration of probabilistic programming applicable whenever one must deal with problems based on uncertain or incomplete knowledge. The scope of possible applications is obviously much broader than robotics.     

Silica based polishing of {100} and {111} single crystal diamond

Diamond is one of the hardest and most difficult to polish materials. In this paper, the polishing of {111} and {100} single crystal diamond surfaces by standard chemical mechanical polishing, as used in the silicon industry, is demonstrated. A Logitech Tribo Chemical Mechanical Polishing system with Logitech SF1 Syton and a polyurethane/polyester polishing pad was used. A reduction in roughness from 0.92 to 0.23 nm root mean square and 0.31 to 0.09 nm rms for {100} and {111} samples respectively was observed.     

Ant colony optimisation of decision tree and contingency table models for the discovery of gene–gene interactions

In this study, ant colony optimisation (ACO) algorithm is used to derive near‐optimal interactions between a number of single nucleotide polymorphisms (SNPs). This approach is used to discover small numbers of SNPs that are combined into a decision tree or contingency table model. The ACO algorithm is shown to be very robust as it is proven to be able to find results that are discriminatory from a statistical perspective with logical interactions, decision tree and contingency table models for various numbers of SNPs considered in the interaction. A large number of the SNPs discovered here have been already identified in large genome‐wide association studies to be related to type II diabetes in the literature, lending additional confidence to the results.Inspec keywords: genetics, genomics, DNA, polymorphism, molecular biophysics, molecular configurations, ant colony optimisation, decision trees, bioinformatics, diseasesOther keywords: ant colony optimisation, decision tree, contingency table models, gene‐gene interactions, ACO algorithm, near‐optimal interactions, single nucleotide polymorphisms, SNP, genome‐wide association studies, type II diabetes     

On the properness condition for modal analysis of non-symmetric second-order systems

Non-symmetric second-order systems can be found in several engineering contexts, including vibroacoustics, rotordynamics, or active control. In this paper, the notion of properness for complex modes is extended to the case of non-self-adjoint problems. The properness condition is related to the ability of a set of complex modes to represent in an exact way the behavior of a physical second-order system, meaning that the modes are the solutions of a quadratic eigenvalue problem whose matrices are those of a physical system. This property can be used to identify the damping matrices which may be difficult to obtain with mathematical modeling techniques. The first part of the paper demonstrates the properness condition for non symmetric systems in general. In the second part, the authors propose a methodology to enforce that condition in order to perform an optimal reconstruction of the “closest” physical system starting from a given basis complex modes. The last part is dedicated to numerical and experimental illustrations of the proposed methodology. A simulated academic test case is first used to investigate the numerical aspects of the method. A physical application is then considered in the context of rotordynamics. Finally, an experimental test case is presented using a structure with an active control feedback. An extension of the LSCF identification technique is also introduced to identify both left and right complex mode shapes from measured frequency response functions.