Wireless Transport Emulator Based on LINC Software Switch

Recent technological advances in the telecommunications industry have led to discovering the limitations of traditional communication networks and, in this context, to the emergence of a new paradigm that tries to mitigate them, namely software defined networking (SDN). SDN is beginning to infiltrate all the aspects of a network, and all kind of networks, from LANs, campus, enterprise, or mobile operator networks. Since this field is not mature yet, the interest from the academia and industry is very strong, thus having the right tools for research is critical. In this respect, mininet is a very good simulator of software defined networks. A software switch that can emulate optical extensions of SDN has emerged and has been integrated with mininet: LINC-OE. There is a need in the research community for a software switch that can be integrated with mininet and used to emulate wireless transport networks. This paper proposes a solution for that need by extending the LINC-OE for wireless transport: LINC-WE. In this context, two approaches are considered: the first is emulating the wireless links between two nodes and the other is integrating the LINC switch with a NETCONF server, for being able to expose a wireless transport device information model for simulations.     

The study of the electric and magnetic properties of PbZr0.2Ti0.8O3-BiFeO3 multilayers

The results of the electric and magnetic measurements performed on PbZr_0.2Ti_0.8O₃-BiFeO₃ symmetric structures, deposited on Pt/Si wafers, were compared for different number of layers in order to analyse the effect of interfaces over the macroscopic properties. It was found that the shape and magnitude of the capacitance-voltage characteristic, as well as the shape and parameters of the ferroelectric and magnetic hysteresis, depend on the number of interfaces in the intended multilayer structure. A temperature induced gradual transition from a magnetically disordered spin glass like phase of low temperature to an uncompensated antiferromagnetic phase at room temperature takes place in the BiFeO₃ films, under low applied magnetic fields. A partial ferromagnetic like order can be obtained at low temperatures by increasing the field. The observed changes in the electric and magnetic behaviour of the systems were related to an increased degree of disorder for electric dipoles and magnetic moments, due to the increased number of layers and crystallization treatments.     

Porous calcium alginate–gelatin interpenetrated matrix and its biomineralization potential

Artificial bone composites exhibit distinctive features by comparison to natural tissues, due to a lack of self-organization and intimate interaction apatite-matrix. This explains the need of “bio-inspired materials”, in which hydroxyapatite grows in contact with self-assembling natural polymers. The present work investigates the function of a rational design in the hydroxyapatite-forming potential of a common biopolymer. Gelatin modified through intrinsic interactions with calcium alginate led through freeze-drying to porous hydrogels, whose architecture, constitutive features and chemistry were investigated with respect to their role on biomineralization. The apatite-forming ability was enhanced by the porosity of the materials, while the presence of alginate-reinforced Gel elastic chains, definitely favored this phenomenon. Depending on the concentration, polysaccharide chains act as “ionic pumps” enhancing the biomineralization. The mineralization-promoting effect of the peptide-polysaccharide network strictly depends on the hydrogels structural, compositional and morphological features derived from the interaction between the above mentioned two components.     

Electrochemical stability and surface analysis of a new alkyd paint with low content of volatile organic compounds

This paper presents the results regarding the electrochemical stability and surface analysis of a new alkyd paint with low content of volatile organic compounds in comparison with a conventional alkyd paint. The alkyd films were realized on carbon steel substrate. Dry films thickness in 30–35 μm range was obtained. The experimental tests were carried out in 3% NaCl solution at the 25 °C temperature. The electrochemical techniques (electrochemical impedance spectroscopy (EIS), potentiodynamic and Tafel polarization) and surface analysis techniques (AFM, SEM, EDX) were used to evaluate protective properties of the tested paint films. The correlation of all experimental results established that the new alkyd paint with low content of volatile organic compounds presents better protective performances and lower permeability than conventional alkyd paint. AFM, SEM and EDX indicated a compact, homogenous, non-porous and adherent coating.     

Operational Model of the ATLAS TDAQ Network

The ATLAS TDAQ network consists of four separate Ethernet based networks which together total over 4000 ports with 200 edge switches and 6 multi-blade chassis switches at the core. System checks are invoked at every level of the installation. The full installation is described in different static databases. Tools are provided to automatically cross-check these for consistency. The configuration management is centralized: configuration files stored in a database are distributed to all devices and the actual settings are periodically verified. Monitoring systems are deployed to validate the connectivity, identify malfunctions and confirm the resources availability upon request from TDAQ control. Relevant operational statistics (e.g., port status and throughput) are continuously logged and made available to TDAQ control. Watches and alarms are set for dynamic threshold violations and the complete instantaneous status can be viewed at different levels of abstraction in a 3D fly-through. A tool-set has been developed to demonstrate aggregate achievable cross-sectional bandwidth for TDAQ-specific traffic profiles, as well as to analyze traffic flows and hot spot behaviour.     

The remainder in the approximation by a generalized Bernstein operator: a representation by a convex combination of second-order divided differences

We investigate the remainder of the approximation formula of a function f∈C[0,1] by means of a generalized Bernstein operator (1.3), depending on two nonnegative integer parameters, introduced by the author in 1984 in the paper [11]. The remainder is expressed in (2.1)–(2.2) by a formula generalizing the author's earlier representation (1.2) of the remainder in Bernstein's classical approximation formula. In (2.13)–(2.14) an expression is given for the remainder involving a linear functional (2.14) which is a convex combination of second-order divided differences. Received: March 1996 / Accepted: April 1996     

High conversion synthesis of poly(methyl methacrylate)

Summary The possibilities to obtain high conversion in the bulk polymerization of methyl methacrylate a) with an additional initiation through ultrasomation or b) by development of the reaction in a magnetic field, are followed. The realized processes were compared to the classical bulk method. Some properties of the synthesized homopolymers are also presented.     

Magnetic properties of magnetite nanoparticles coated with mesoporous silica by sonochemical method

In this paper we present the magnetic properties of mesoporous silica-coated Fe₃O₄ nanoparticles. The coating of magnetite nanoparticles with mesoporous silica shell was performed under ultrasonic irradiation. The obtained mesoporous silica-coated magnetite nanoparticles were characterized by powder X-ray diffraction, focused ion beam-scanning electron microscopy, nitrogen adsorption-desorption isotherms and vibrating sample magnetometer. The hysteretic behavior was studied using first-order reversal curves diagrams. The X-ray diffraction result indicates that the extreme chemical and physical conditions created by acoustic cavitations have an insignificant effect on crystallographic structural characteristic of magnetite nanoparticles. Changes in the coercivity distributions of the magnetite nanoparticles were observed on the first-order reversal curves diagrams for the samples with coated particles compared with the samples containing uncoated particles of magnetite. The coated particles show an increased most probable coercivity of about 20% compared with the uncoated particles which can be associated with an increased anisotropy due to coating even if the interaction field distribution measured on the diagrams are virtually identical for coated/uncoated samples.