Proton Transport in Electrospun Hybrid Organic–Inorganic Membranes: An Illuminating Paradox

Chemistry and processing have to be judiciously combined to structure the membranes at various length scales to achieve efficient properties for polymer electrolyte membrane fuel cell to make it competitive for transport. Characterizing the proton transport at various length and space scales and understanding the interplays between the nanostructuration, the confinement effect, the interactions, and connectivity are consequently needed. The goal here is to study the proton transport in multiscale, electrospun hybrid membranes (EHMs) at length scales ranging from molecular to macroscopic by using complementary techniques, i.e., electrochemical impedance spectroscopy, pulsed field gradient‐NMR spectroscopy, and quasielastic neutron scattering. Highly conductive hybrid membranes (EHMs) are produced and their performances are rationalized taken into account the balances existing between local interaction driven mobility and large‐scale connectivity effects. It is found that the water diffusion coefficient can be locally decreased (2 × 10^?6 cm² s^?1) due to weak interactions with the silica network, but the macroscopic diffusion coefficient is still high (9.6 × 10^?6 cm² s^?1). These results highlight that EHMs have slow dynamics at the local scale without being detrimental for long‐range proton transport. This is possible through the nanostructuration of the membranes, controlled via processing and chemistry.     

Information and Telecommunications Project for a Digital City: A Brazilian case study

Making information and telecommunications available is a permanent challenge for cities concerned to their social, urban and local planning and development, focused on life quality of their citizens and on the effectiveness of public management. Such a challenge requires the involvement of everyone in the city. The objective is to describe the information and telecommunications project from the planning of a digital city carried out in Vinhedo-SP, Brazil. It was built as a telecommunications infrastructure of the kind of “open access metropolitan area networks” which enables the integration of citizens in a single telecommunications environment. The research methodology was emphasized by a case study which turned to be a research-action, comprising the municipal administration and its local units. The results achieved describe, by means of a methodology, the phases, sub-phases, activities, approval points and resulting products, and formalize their respective challenges and difficulties. The contributions have to do with the practical feasibility of the project and execution of its methodology. The conclusion reiterates the importance of the project, collectively implemented and accepted, as a tool to help the management of cities, in the implementation of Strategic Digital City Projects, in the decisions of public administration managers, and in the quality of life of their citizens.     

Simultaneous measurement of temperature and strain based on arc-induced long-period fibre gratings

A study on arc-induced long-period fibre gratings (LPFGs) revealed that their strain sensitivity depends on the electric current of the arc discharge. Based on that property, a sensor scheme comprising two concatenated LPFGs was implemented for discrimination of temperature and strain effects. This sensor presented resolutions of /spl plusmn/0.1/spl deg/C//spl radic/Hz and /spl plusmn/35 /spl mu//spl epsiv///spl radic/Hz, respectively.     

Performance effects of innovative IT applications over time

There is evidence to indicate that the effects of new product and service innovations change over time as a result of learning and competition. However, there have not been any studies of the effects of learning and competition on the impacts of innovative information technology (IT) applications. This paper presents the results of an extensive study of the effects of very early investments in automated teller machines (ATMs) by banks, on market share and overall bank performance. The study spans the period from 1971 to 1984 and includes 2534 banks from across the United States. The results indicate that the impacts of early ATM investments can best be described by exponential and logistic models, indicating that the benefits were very small at first, but increased rapidly after a few years. In addition, the benefits obtained by the earliest adopters were larger than those obtained by the banks that adopted later. These results have important implications for IT investment decisions. The results also suggest that cross-sectional studies, conducted soon after an application is installed, may fail to find benefits even if large benefits are obtained     

Blocage par injection de modes sous- harmoniques d’un oscillateur utilisant une ligne à retard à ondes de surface

A nonlinear regeneration pulsed oscillator driven by a monochromatic source has been built. Subharmonics of the resonance carrier/modulation are measured with an accuracy of 10^-10 thanks to the use of a double beats measurement set-up. The multiscale analysis of frequency readings reveals a rich fine structure which is in agreement with the nonlinear topological approach of synchronized states.     

Delay sensing for long-term variations and defects monitoring in safety–critical applications

The impact of parametric variations on digital circuit performance is increasing in nanometer Integrated Circuits (IC), namely of Process, power supply Voltage and Temperature (PVT) variations. Moreover, circuit aging also impacts circuit performance, especially due to Negative Bias Temperature Instability (NBTI) effect. A growing number of physical defects manifest themselves as delay faults (at production, or during product lifetime). On-chip, on-line delay monitoring, as a circuit failure prediction technique, can be an attractive solution to guarantee correct operation in safety–critical applications. Safe operation can be monitored, by predictive delay fault detection. A delay monitoring methodology and a novel delay sensor (to be selectively inserted in key locations in the design and to be activated according to user’s requirements) is proposed, and a 65 nm design is presented. The proposed sensor is programmable, allowing delay monitoring for a wide range of delay values, and has been optimized to exhibit low sensitivity to PVT and aging-induced variations. Two MOSFET models—BPTM and ST—have been used. As abnormal delays can be monitored, regardless of their origin, both parametric variations and physical defects impact on circuit performance can be identified. Simulation results show that the sensor is effective in identifying such abnormal delays, due to NBTI-induced aging and to resistive open defects.     

A network of electronic neural oscillators reproduces the dynamics of the periodically forced pyloric pacemaker group

Low-dimensional oscillators are a valuable model for the neuronal activity of isolated neurons. When coupled, the self-sustained oscillations of individual free oscillators are replaced by a collective network dynamics. Here, dynamical features of such a network, consisting of three electronic implementations of the Hindmarsh-Rose mathematical model of bursting neurons, are compared to those of a biological neural motor system, specifically the pyloric CPG of the crustacean stomatogastric nervous system. We demonstrate that the network of electronic neurons exhibits realistic synchronized bursting behavior comparable to the biological system. Dynamical properties were analyzed by injecting sinusoidal currents into one of the oscillators. The temporal bursting structure of the electronic neurons in response to periodic stimulation is shown to bear a remarkable resemblance to that observed in the corresponding biological network. These findings provide strong evidence that coupled nonlinear oscillators realistically reproduce the network dynamics experimentally observed in assemblies of several neurons.     

Suppression of phonon‐mediated hot carrier relaxation in type‐II InAs/AlAsxSb1 − x quantum wells: a practical route to hot carrier solar cells

InAs/AlAs_xSb_{1 − x} quantum wells are investigated for their potential as hot carrier solar cells. Continuous wave power and temperature‐dependent photoluminescence indicate a transition in the dominant hot carrier relaxation process from conventional phonon‐mediated carrier relaxation below 90 K to a regime where inhibited radiative recombination dominates the hot carrier relaxation at elevated temperatures. At temperatures below 90 K, photoluminescence measurements are consistent with type‐I quantum wells that exhibit hole localization associated with alloy/interface fluctuations. At elevated temperatures, hole delocalization reveals the true type‐II band alignment, where it is observed that inhibited radiative recombination due to the spatial separation of the charge carriers dominates hot carrier relaxation. This decoupling of phonon‐mediated relaxation results in robust hot carriers at higher temperatures, even at lower excitation powers. These results indicate type‐II quantum wells offer potential as practical hot carrier systems. Copyright © 2016 John Wiley & Sons, Ltd.     

A survey on nonlinear analog-to-digital converters

This paper presents a survey on Nonlinear Analog-to-Digital converters (ADC). This class of converters is extremely relevant in applications where there is a need for non-uniform quantization characteristic, for example, some specific applications in the areas of light detection, hearing aid, nuclear physics, image acquisition, communication systems, etc. This survey outlines the state-of-the-art Nonlinear ADC topologies, such as, floating point, logarithmic, piecewise linear and oversampled nonlinear converters, and discusses their performance and advantages in terms of their applications.     

Multicast deflector

Technological evolution is leading telecommunications toward all-IP scenarios, where multiple services are transported as IP packets. Among these services is the broadcast of video. A possible mechanism for broadcasting multiple video channels over IP is to use IP multicast, and let each client decide about the reception of a channel. The secure IP multicast specified by the IETF MSEC working group is a candidate solution for securing these broadcast services. In this paper we propose a new solution for supporting the broadcast of multiple video channels which can be accessed only by authorized users; besides, when a video channel is not visualized in the last mile its transmission is temporarily suspended, so that the cable can be used for other services such as standard Internet access.