Application of vibrational spectroscopy for the analysis of polymer composites

Various examples of filled elastomeric networks will illustrate the potential of Fourier-transform infrared spectroscopy for a better understanding of the properties of elastomeric composite materials which are two-phase materials. The addition of an inorganic component to polymers leads to improvements in various physical and mechanical properties. These improvements are the result of a complex interplay between the properties of the individual constituent phases : the polymer, the filler and the interfacial region. Infrared spectroscopy has been used to characterize the interface in the isotropic state and also under uniaxial extension.     

Performance Analysis of Communication System with Nonlinear Power Amplifier

A communication system with nonlinear Power Amplifier (PA) is considered. The PA nonlinearity forces the designer of communication system to choose proper Back-Off, which influences three major parameters of the communication system: (i) power efficiency, (ii) Adjacent Channel Power Ratio (ACPR), and (iii) bit rate expressed by Mutual Information (MI). Having these three parameters, we propose to evaluate the performance of a communication system with nonlinear PA using the fact that ACPR is dictated by the regulator/communication standard. In what follows we propose to find power efficiency and MI as a function of ACPR. To illustrate the usefulness of the proposed method, the Solid State Power Amplifier (SSPA), and two linearized versions of SSPA are considered. The first version is a perfectly linearized PA using pre-distortion resulting with Soft Envelope Limiter (SEL), and the second is the Feed-Forward (FF) architecture based on SSPA. For each of the PAs ACPR, power efficiency and MI are found. While the analysis of SSPA and SEL is mainly based on the existing literature, the analysis of FF may be considered as a new contribution. From the results of the analysis it is concluded that linearization improves the overall performance of communication system. It is also shown that the pre-distortion method (SEL) shows better performance than FF.     

Continuous Markovian Model for Unexpected Shift in SPC

Various process models for discrete manufacturing systems (parts industry) can be treated as bounded discrete-space Markov chains, completely characterized by the original in-control state and a transition matrix for shifts to an out-of-control state. The present work extends these models by using a continuous-state Markov chain, incorporating non-random corrective actions. These actions are to be realized according to the statistical process control (SPC) technique and should substantially affect the model. The developed stochastic model yields Laplace distribution of a process mean. Real-data tests confirm its applicability for the parts industry and show that the distribution parameter is mainly controlled by the SPC sample size.     

Fuzzy logics based on [0,1)-continuous uninorms

Axiomatizations are presented for fuzzy logics characterized by uninorms continuous on the half-open real unit interval [0,1), generalizing the continuous t-norm based approach of Hájek. Basic uninorm logic BUL is defined and completeness is established with respect to algebras with lattice reduct [0,1] whose monoid operations are uninorms continuous on [0,1). Several extensions of BUL are also introduced. In particular, Cross ratio logic CRL, is shown to be complete with respect to one special uninorm. A Gentzen-style hypersequent calculus is provided for CRL and used to establish co-NP completeness results for these logics. Research supported by Marie Curie Fellowship Grant HPMF-CT-2004-501043.     

A socio-cognitive model of trust using argumentation theory

Trust is used to minimise the uncertainty in the interactions of the agents especially in case of conflicting information from different sources. Besides conflicts among information there can also be conflicts about the trust attributed to the information sources. In this paper, we discuss how to reason about trust using argumentation theory, so to express also the possibly conflicting motivations about trust and distrust. The methodology of meta-argumentation allows us to model both information and information sources as arguments and to argue about them. First, we present a model for representing evidence provided as motivation of the sources’ arguments to represent the need of a trusted source to believe the information, and we show how to model the information sources in a way that it can be argued whether they should be considered trustworthy or not. Second, we provide a focused representation of trust about the sources in which trust concerns not only the sources but also the information items and the relation with other information. Third, we introduce the feedback on the trustworthiness of the sources and the information items they propose, such that an attack to the trustworthiness of the items feeds back on the trustworthiness of the source. Finally, we distinguish two dimensions of trust, namely competence and sincerity, and we present a formal way to express those dimensions, only informally described in the socio-cognitive models of trust.     

Hydration behavior of C2S and C2AS nanomaterials, synthetized by sol–gel method

Hydration behavior of dicalcium silicate (C₂S) (Cement chemistry nomenclature is used where C=CaO, S=SiO₂, A=Al₂O₃, S=SO₃) and gehlenite (C₂AS), synthesized by sol–gel method was investigated by means of isothermal heat flow calorimeter at different temperatures. These phases were obtained by crystallization processing at different temperatures from their xerogels (nano-crystalline) prepared by the sol–gel method at ambient temperature. The crystallization of C₂S begins below 600°C and it is well crystallized at 900°C. X-ray diffraction patterns reveal that β-C₂S is formed and it remains stable since after slow cooling. The crystallization of C₂AS xerogels starts with the formation of C₂S, then it reacts with alumina to form mineral C₂AS at 1100°C. The effect of hydration temperature upon the hydration reaction of C₂S obtained at 600 and 900°C and C₂AS annealed at 600 and 1100°C was investigated by means of isothermal calorimeter. An increase in the temperature of hydration brought about initial acceleration of all samples, as indicated by the increased magnitude of peak of calorimetric curves. The microstructure of the samples cured at hydrothermal condition after 1 and 7 days has been examined by means of scanning electron microscopy (SEM). Fine crystals of calcium silicate hydrate (C–S–H) were developed in C₂S samples, while C₂AS has been hydrated to form gehlenite hydrate supplemented by C–S–H.     

The deBranges theorem and uniqueness statements

Recently deBranges gave a very remarkable proof of Milin’s conjecture. This implies both the conjectures of Robertson and Bieberbach. It is our aim to show that the statement of equality case in both Robertson’s and Bierbach’s conjectures may be proved by a different and easier method.     

Photooxygenations par transfert d'electron sensibilisees par le dicyano-9,10 anthracene. Role du solvant et formation d'oxygene singulet.

Photooxygenation of naphtalenic compounds sensitized by electron acceptors like 9,10 dicyanoanthracene (DCA) is shown to proceed by two distinct ways depending on the solvent polarity. In a polar solvent superoxide ion (O₂^-.) as well as singlet oxygen (¹O₂★) are involved while in a non polar solvent only singlet oxygen is produced.