N‐(2‐biphenylenyl)‐4‐[2′‐phenylethynyl] phthalimide: 2. Detailed study of the monomer cure and properties of the resulting polymer

A detailed study is presented of the high‐temperature cure of the difunctional monomer N‐(2‐biphenylenyl)‐4‐[2′‐phenylethynyl]phthalimide (BPP) and the thermal properties of the resulting homopolymer. Although the phenylethynyl groups are consumed within 1 h at 370 °C, other reactions continue well after this, leading to a cured polymer whose glass transition temperature (T_g) is highly dependent on cure time and temperature. A T_g of 450 °C is achieved after a 16 h cure at 400 °C. Use of chemometrics to analyse the infrared spectra of curing BPP provides evidence for changes in the aromatic moieties during cure, perhaps indicative of co‐reaction between the biphenylene and phenylethynyl groups; however, other processes also contribute to the overall complex cure mechanism. Despite the high T_g values, BPP homopolymer exhibits unacceptably poor thermo‐oxidative stability at 370 °C, showing a weight loss of about 50 % after 100 h ageing. This is perhaps a result of formation of degradatively unstable crosslink structures during elevated‐temperature cure. Copyright © 2004 Society of Chemical Industry     

Improving video QoE with IP over ICN

Information‐centric networking (ICN) has long been advocating for radical changes to the Internet, but the upgrade challenges that these entail have hindered its adoption. To break this loop, the POINT project proposed a hybrid, IP‐over‐ICN, architecture: IP networks are preserved at the edge, connected to each other over an ICN core. This exploits the key benefits of ICN, enabling individual network operators to improve the performance of their IP‐based services, without changing the rest of the Internet. This paper first provides an overview of POINT and outlines how it can improve upon IP in terms of performance and resilience. It then describes a trial of the POINT prototype in a production network, where real users operated actual IP‐based applications. As part of the trial, we carried out experiments to evaluate the quality of experience (QoE) for video services offered via either HLS or IPTV, using either IP or POINT as a substrate. The results from the trial verify that the IP‐over‐ICN approach of POINT offers enhanced QoE to the users of these video services, compared with traditional IP, especially under exceptional network conditions.     

Copyright liability for users and distributors of content sharing and communication technologies: a crossroads between past and present

In the last decade or so, society has seen the beginnings of a digital revolution where innovation and technological advancement met and changed the way in which people use digital technology. This has only increased the ambit of confusion between the law and technology innovation. This is evident with the creation and distribution of content sharing and communication technologies such as peer-to-peer, network distributive systems, file sharing software and other technology enabling software where users are able to share and access information. The recurring issues that appear throughout case precedent have reinforced the uncertainty and confusion over the interpretation of authorisation. This paper will explore the concept of authorisation and evaluate the courts' interpretation of what constitutes an authorisation of infringement with respect to technology innovators of communication technologies. This will be achieved through a discussion of the cases that explored ‘authorisation’ through the genealogy of authorisation. It is important to discuss the history of authorisation first, and then evaluate how the courts have interpreted ‘authorisation’. This paper will demonstrate how the interpretation of authorisation has created ambiguity and uncertainty for technology innovators and developers.     

Asymptotic homogenization modeling and analysis of effective properties of smart composite reinforced and sandwich shells

General micromechanical models for smart composite shells with periodically arranged actuators and varying thickness are developed using the asymptotic homogenization techniques. The models make it possible to determine both local fields, i.e., stresses, strains and displacements, and effective elastic and piezoelectric coefficients of the smart composite shells. It is shown that the original boundary value problem decouples into a set of simpler problems, known as unit cell problems. In particular, it is the solution of these unit cell problems that yields the aforesaid effective coefficients. These coefficients are universal in nature and may be used to study a wide variety of boundary value problems associated with a given smart composite structure. The derived models and the expressions for the effective coefficients are illustrated by means of four examples pertaining to hexagonal honeycomb sandwich structures and rectangular-reinforced, diagonally restrained and triangular-reinforced smart wafer shells. These structures are endowed with piezoelectric carrier layers made of orthotropic material and isotropic core or wafer. It is shown that the derived models can be used to tailor the effective properties of such smart composite structures to meet the requirements of particular applications of interest.     

The time dependent resistance and inductance of the electricdischarges in pulsed gas lasers

A method of finding the time dependent resistances and inductances in the discharges in pulsed gas lasers is described in this work. According to this method the waveforms of the laser circuit voltages are digitized and their first and second derivatives are calculated. These are substituted into the differential equations governing the behavior of the system and relationships among the resistances and inductances are formed for every time. Using relationships from a sequence of four very closed adjacent time instants and considering that during this short time interval the resistances and inductances are varied linearly, their values can be found for this particular time interval. Repeating the same procedure for other time intervals and scanning the entire time region of the discharge, the time histories of the resistances and inductances of the discharges are revealed. These show strong variations in the “formation phase” of the discharge (first 50 nsec). Specifically the resistances drop rapidly (first 10 nsec) from very high values to low values, while the inductances increase to high values and subsequently decrease, forming an abrupt high peak. The steep drop of the resistances is due to the electron avalanche multiplication, while the peak of the inductances is due to the centripetal magnetic forces (Laplace forces), which cause a temporary constriction of the plasma. In the “main phase” of the discharge the resistances present a damping oscillation with the same frequency as the voltages, while the inductances present light fluctuations around constant values     

The inductance and resistance of the laser discharge in a pulsedgas laser

Theoretical consideration of the discharge of a laser channel takes place in this work. This leads to formulas for the resistance and inductance. The resistance depends on the total charge in the discharge volume while the inductance depends on the dimensions of the discharge volume. Generally, the inductance increases as electrode length and discharge thickness decreases and more so as these become equal. On the other hand the inductance increases as interelectrode distance increases. However, discharge dimensions depend on the drift velocity of the flowing charges creating centripetal Lorenztian forces which constrict the volume of the laser channel. Consequently, the microscopic parameters of the plasma, total charge and drift velocity are responsible for the electrical macroscopical characteristics' resistance and inductance respectively. Nevertheless, these microscopic parameters are formed through the external driving circuit and especially through its capacitance which strongly influences the discharge of the laser channel. Particularly, the values of the capacitances form the total charge, while the coupling of the capacitances in the circuit forms the drift velocity. These were inferred dealing with the two most common circuits used in pulsed gas lasers, namely the “doubling circuit” and the “charge transfer circuit” for all possible combinations of capacitance allocation     

A mobility toolbox architecture for all-IP networks: an ambient networks approach [architectures and protocols for mobility management in all-IP mobile networks]

The future Internet will need to cater to an increasing number of mobile devices and mobile networks, roaming across different access networks and trust domains. In addition, various limitations imposed by the end user, service provider, or network operator agreements and preferences will need to be considered. A plethora of mobility management protocols have been proposed to handle different and mostly limited sets of these mobility requirements. In this article we make the case for coexistence of mobility protocols in order to support the large range of mobility scenarios possible in future all-IP networks. This coexistence takes the form of a mobility toolbox that enables mobility handling mechanisms to be selected according to the context. We then present a design for the mobility toolbox as a component of the ambient networks architecture, including a simplified mobility tool interface toward protocol modules, and show how it meets the requirements of future all-IP networks. We further demonstrate the feasibility and performance gains of the mobility toolbox architecture with a prototype implementation based on network mobility.     

AQUA: An Amphibious Autonomous Robot

AQUA, an amphibious robot that swims via the motion of its legs rather than using thrusters and control surfaces for propulsion, can walk along the shore, swim along the surface in open water, or walk on the bottom of the ocean. The vehicle uses a variety of sensors to estimate its position with respect to local visual features and provide a global frame of reference