Characteristics and evaluation criteria of substrate-based manufacturing. Is roll-to-roll the best solution for printed electronics?

The vast majority of publications covering the manufacturing of printed electronics employ a web-fed roll-to-roll process. However, other principles of substrate transport are well established in printing science and industry. The focus on roll-to-roll in the scientific community therefore remains ambiguous. In an attempt to structure the discussion about upscaling organic electronics production, we extend existing classifications of substrate-based manufacturing, which is not limited to the field of printed electronics. Production processes can be classified by five key components: manufacturing technology, contact topology, substrate transport, substrate velocity, substrate feed and the degree of integration. This paper reviews four different substrate transport principles: roll-to-roll, sheet-to-sheet, sheets-on-shuttle and hybrid forms like roll-to-sheet. Besides basic working principles, both chances and limitations are discussed. Due to their individual complexity, a sound comparison ought not be reduced to a few key figures. In fact, the selection of the substrate transport requires an in-depth analysis of the individual production process. To aid decision-making, we introduce a hierarchy of 19 attributes covering aspects of production flexibility, quality, reliability, productivity and operations.     

Internet phone — changing the telephony paradigm?

This paper provides an overview of the history, current status, and underlying technology of Internet telephony — the transport of speech information over a packet-switched connectionless network. The economics of Internet telephony and a number of possible system architectures for interconnection with the switched telephone network are examined. The paper concludes with a look at the quality of service issues raised by Internet telephony.     

Performance evaluation of the rate‐based flow control mechanism for ABR service

In this paper we investigate the performances of the EFCI‐based (Explicit Forward Congestion Indication) and ER‐based (Explicit Rate) algorithms for the rate‐based flow control of the ABR (Available Bit Rate) traffic in an ATM network. We consider the case of two switches in tandem. We present several definitions of a bottleneck, and provide conditions that determine whether the first, the second or both queues are bottleneck. We show that it is not necessarily the queue with the slowest transmission rate in which congestion actually occurs. We derive analytic formulas for the maximum queue length. We compare our results to those obtained by approximating a network by a simpler one, containing only the bottleneck switch. We show that the maximum queue lengths under the approximating approach may largely underestimate the ones obtained in the real network. This revised version was published online in June 2006 with corrections to the Cover Date.     

Architectural Options for the Next-Generation Networking Paradigm: Is Optical Internet the Answer?

Recent advances in optical networking technologies are setting the foundation for the next-generation data-centric networking paradigm, an “Optical Internet”. This work addresses one of the most challenging issues facing today's service providers and data vendors; how will the SONET/SDH-based legacy infrastructure currently in place make a graceful transition to the next generation networking paradigm?

A simplified, two-tiered architecture that requires two types of sub-systems will set the stage for a truly optical internet: service delivery platforms that enforce service policies; and transport platforms that intelligently deliver the necessary bandwidth to these service platforms. If IP can be mapped directly onto the WDM layer, some of the unnecessary network layers can be eliminated, opening up new possibilities for the potential of collapsing today's vertically layered network architecture into a horizontal model where all network elements work as peers to dynamically establish optical paths through the network. This paper presents a balanced view of the vision of the next-generation optical internet

The work presented here builds on the IETF multi-protocol lambda switching (MPλS) initiative and addresses the implementation issues of the path selection component of the traffic-engineering problem in a hybrid IP-centric DWDM-based optical network. An overview of the methodologies and associated algorithms for dynamic lightpath computation is presented. Specifically, we show how the complex problem of real-time provisioning of optical channels can be simplified by using a simple dynamic constraint-based routing and wavelength assignment (RWA) algorithm that compute solutions to three sub-problems: (a) routing; (b) constrained-based shortest-route selection; (c) wavelength assignment.

We present two different schemes for dynamic provisioning of the optical channels. The two schemes use the same dynamic lightpath computation approach proposed here, except that the third component, that is the wavelength assignment algorithm and its implementation, is different for each of the two schemes.

     

Is accurate recording of the ECG surface Laplacian feasible?

Experimental and model studies were performed to measure the electrocardiographic surface Laplacian using a rectangular finite difference approximation. The experimental approach used ten normal subjects with two sites on the torso. Electrode spacing was 2 cm. The surface Laplacian is theoretically independent of rotation of the electrode array. The data showed considerable variation with rotation. Model studies employed a realistic 23-dipole source. A spherical volume conductor showed invariance with rotation, as anticipated theoretically. A realistic torso, however, showed variation with rotation, although not as severe as that measured. A separate experimental study considered the signal-to-noise ratio (SNR) for the surface Laplacian. The average SNR was 3.3 and 2.5 at the two sites. These results raise serious questions about the practical ability to measure the surface Laplacian on the torso.     

Game of protocols: Is QUIC ready for prime time streaming?

Quick User Datagram Protocol (UDP) Internet Connections (QUIC) is an experimental and low‐latency transport protocol proposed by Google, which is still being improved and specified in the Internet Engineering Task Force (IETF). The viewer's quality of experience (QoE) in HTTP adaptive streaming (HAS) applications may be improved with the help of QUIC's low‐latency, improved congestion control, and multiplexing features. We measured the streaming performance of QUIC on wireless and cellular networks in order to understand whether the problems that occur when running HTTP over TCP can be reduced by using HTTP over QUIC. The performance of QUIC was tested in the presence of network interface changes caused by the mobility of the viewer. We observed that QUIC resulted in quicker start of media streams, better streaming, and seeking experience, especially during the higher levels of congestion in the network and had a better performance than TCP when the viewer was mobile and switched between the wireless networks. Furthermore, we measured QUIC's performance in an emulated network that had a various amount of losses and delays to evaluate how QUIC's multiplexing feature would be beneficial for HAS applications. We compared the performance of HAS applications using multiplexing video streams with HTTP/1.1 over multiple TCP connections to HTTP/2 over one TCP connection and to QUIC over one UDP connection. To that effect, we observed that QUIC provided better performance than TCP on a network that had large delays. However, QUIC did not provide a significant improvement when the loss rate was large. Finally, we analyzed the performance of the congestion control mechanisms implemented by QUIC and TCP, and tested their ability to provide fairness among streaming clients. We found that QUIC always provided fairness among QUIC flows, but was not always fair to TCP.     

Toward a document evaluation methodology: what does research tellus about the validity and reliability of evaluation methods?

Although the usefulness of evaluating documents has become generally accepted among communication professionals, the supporting research that puts evaluation practices empirically to the test is only beginning to emerge. This article presents an overview of the available research on troubleshooting evaluation methods. Four lines of research are distinguished concerning the validity of evaluation methods, sample composition, sample size, and the implementation of evaluation results during revision     

Statistical Properties for the Envelope and Phase of the α ? η ? μ Generalized Fading Channels

In this paper, a study on the statistical properties for the envelope and phase of both formats of the ?? ? ?? ? ?? generalized fading channels is provided by deriving novel closed-form expressions. Specifically, a simple and closed-form expression for the phase crossing rate of the ?? ? ?? ? ?? generalized fading channels is obtained. Moreover, exact analytical expressions for the level crossing rate and the average duration of fades, as well as the PDF of random FM noise are presented. Confirmation of the provided analytical formulations is attained by reducing the general model to some widely known special cases (Nakagami-m, Hoyt, and Rayleigh). Extra validation is performed by means of a sample of numerical results obtained by Monte Carlo simulation.     

What do we want specifically from the cell phone? An age related study

This study investigated the evolution of specific cell phone feature preferences among high school, undergraduate and graduate college students in Finland. Following the relevant literature review, the paper analyzed the responses of 118 high school, 268 undergraduate and 84 graduate students from educational institutions located in the metropolitan area of Tampere, Finland. The results indicate that the students in Finland appreciate the specific feature “clock”, “phone”, “high battery life”, “alarm”, and “calendar” as very important, and the specific features “TV connectivity”, “joystick”, “live TV”, “Twitter”, and “small screen size” as unimportant features. There were also significant differences in the specific feature preferences between the students between high school, undergraduate and graduate students. In addition there were differences in the way the respondents conceptualize the specific feature preferences of the cell phone. The paper concludes with a discussion regarding the academic and managerial implications.     

What is the Value of Limited Feedback for Next Generation of Cellular Systems?

Wireless Personal Communications - The demand for higher data traffic is exponentially growing. Since last 2 years or so, new research movements have emerged towards LTE-B (Release 13 and...     

The Internet: Is it a replicable technological and social phenomenon for central Europe and the Commonwealth of Independent States?

The Internet is more than just inter-connectivity between computers across geo-political boundaries. The Internet is also a means of exchanging ideas to augment human endeavor. This paper explores conditions for, and possible benefits of, the evolution of the Internet in Central and Eastern Europe and the Commonwealth of Independent States.     

Do the high-frequency indexes of HRV provide a faithful assessment of cardiac vagal tone? A critical theoretical evaluation

When spectral analysis of the heart rate (HR) signal is performed, it is quite common to attribute the HF indexes of heart rate variability (HRV) to cardiac vagal control. The paradigm underlying this attribution states that changes in cardiac vagal outflow correspond to a proportional change in respiratory sinus arrhythmia (RSA). However, recent studies have demonstrated that variations in these indexes do not necessarily reflect proportional changes in vagal tone. The current study provides a theoretical evaluation of the relationship between mean HR, RSA, and cardiac vagal tone. This evaluation is based on a theoretical model, which quantifies the differential effects of vagal blockade by a competitive muscarinic antagonist on the HF indexes of HRV. The model relies on several assumptions that reflect the basic physiology of the sinoatrial (SA) node, as well as pharmacological relations that describe agonist/antagonist equilibrium at the SA receptors. The mathematical framework of this model is the integral-pulse-frequency-modulation (IPFM) process, and its derivations lead to a specific expressions for the dependence of HF and mean HR on the level of vagal blockade. These expressions provide a new insight into the relationship between mean HR, RSA, and vagal tone, and explain conflicting experimental results previously published.     

Design of the Test System for the Dynamic Function of the SLC PCB

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IMT-Adv: Is There a Role for Satellites?

The present paper is intended to discuss the satellite features which could lead to beneficial integration with IMT-Adv. The satellite roles are consistent with: (1) Navigation for Location Based Services (2) Earth observation for GIS-related applications/solutions and (3) Telecommunication. The development of the market is also boosted by the emerging synergies between navigation, communication and information technology in what is called “info-mobility”. The area of discussion is therefore quite wide and we can offer a survey trying to analyse only the aspect which are pertinent with the title of the paper. We therefore apologise if the reader cannot find all information he could be interested in, but we hope to have been capable to close just a bit of the enlarging gap between terrestrial and satellite interests.

The diffusivity of the vacancy in silicon: Is it fast or slow?

Vacancies in silicon are known to be highly mobile both at high temperatures (just below the melting point) and at cryogenic temperatures. Contrary to this, however, vacancy diffusivity near 800 °C — as deduced from the radiation-enhanced self-diffusion coefficient D_sd — was reported to be surprisingly low. An apparent explanation of this contradiction is that the defect concentrations (and accordingly D_sd) are reduced by an impurity-mediated recombination of vacancies and self-interstitials. This effect however is shown to be insufficient to account for such a low D_sd. A suggested solution to the puzzle is that self-interstitials (and vacancies as well) exist in two structural forms, a localized one and an extended one, of strongly differing diffusivities. A low diffusivity manifested in radiation-enhanced self-diffusion is likely to correspond to a low apparent diffusivity of self-interstitials (averaged over the two forms) rather than that of vacancies. The fast and slow forms of vacancies are concluded to be both of a high diffusivity at elevated temperatures while it is most likely that one of them (the extended one) becomes practically immobile at low temperatures.