Creating an intelligent optical network worldwide interoperability demonstration

The Optical Internetworking Forum (OIF) conducted a world interoperability demonstration in conjunction with SUPERCOMM held in Chicago June 22-24, 2004. The demonstration was executed on a global stage with seven carriers across three continents internetworking through an intelligent control plane in a multivendor environment of 15 vendor participants. OIF's demonstration successfully included dynamic end-to-end connection management between client devices and transport network elements in a multidomain, multinode environment. The global connectivity included network elements (NEs) that incorporated the OIF optical user-to-network interface (UNI) and external network-to-network interfaces (E-NNI) among various vendors. Furthermore, carriers were able to test the new Ethernet over synchronous optical network/synchronous digital hierarchy (SONET/SDH) capabilities utilizing the generic framing procedure (GFP-F), virtual concatenation (VCAT), and the link capacity adjustment scheme (LCAS), based on International Telecommunication Union - Telecommunication Standardization Sector (ITU-T) recommendations. This article described the technical approach and execution of this demonstration.     

An analysis of the effect of a reliability paradigm shift on leading British aerospace companies

The aerospace industry is moving towards a new paradigm for the statement of reliability specifications. This paradigm is not a technical metric inherent to a system in isolation, but rather encompasses the wider objectives, operational profile and logistic priorities of its customer. This customer focus is encapsulated in the metrics Failure Free Operating Period and Maintenance Free Operating Period. These metrics describe the duration of effective system operation, in the first case for systems where faults and maintenance are permitted and in the second for systems where faults may not be repaired. As part of the Department of Trade and Industry (DTI) funded Aerospace Project for Insertion of Reliability (ASPIRE) research programme, which itself is part of the Ultra Reliable Aircraft (URA) programme, representatives of leading aerospace companies were interviewed about their opinion n how this new reliability paradigm and associated concepts would affect their way of doing business and their engineering processes. It would appear that the aerospace industry is ready for a move to a more realistic set of reliability metrics and away from the old style MTBF based metrics. This sea change would most likely be welcomed by customers, but as yet the manufacturing companies are unconvinced that such a radical move would be a good thing. Much of the resistance to change is due to old‐fashioned, but well entrenched, beliefs in the traditional way of doing things. A move away from this would bring freshness to the industry and lead to cost and time savings as the traditional approach is dropped in favour of a more planned and thought out approach. Copyright © 2002 John Wiley & Sons, Ltd.     

A review of particulate reinforcement theories for polymer composites

A concerted survey is presented of the existing theories for predicting the strength and modulus of particulate-filled polymeric composites. The macroscopic behaviour of particulate composites is affected by the size, shape, and the distribution of the inclusions. The interfacial adhesion between the matrix and inclusion is also important. The limitation of theoretical models in describing these parameters and expressing the experimental data on the macroscopic behaviour is demonstrated.     

General entropy criteria for inverse problems, with applications todata compression, pattern classification, and cluster analysis

Minimum distance approaches are considered for the reconstruction of a real function from finitely many linear functional values. An optimal class of distances satisfying an orthogonality condition analogous to that enjoyed by linear projections in Hilbert space is derived. These optimal distances are related to measures of distances between probability distributions recently introduced by C.R. Rao and T.K. Nayak (1985) and possess the geometric properties of cross entropy useful in speech and image compression, pattern classification, and cluster analysis. Several examples from spectrum estimation and image processing are discussed     

Operating principles of a novel multiphase multimotor vector-controlled drive

Independent flux and torque control of an ac machine can be achieved by means of vector control, utilizing only two stator d-q current components. Consequently, in ac machines with a phase number greater than three, there exist additional degrees of freedom. Although they can be used to enhance the torque production of a multiphase machine through injection of higher stator current harmonics, an entirely different purpose is possible as well. The additional degrees of freedom can be utilized to control independently other machines within a multimotor drive system. In order to do so, it is necessary to connect stator windings of all the multiphase machines in series, with an appropriate phase transposition, apply a vector control algorithm to each machine separately, and supply the stator windings of the multi-machine system from a single current controlled voltage source inverter (VSI). Inverter current control is performed in the stationary reference frame, using inverter phase currents. The foundations of the concept are set forth in the paper, for an arbitrary odd n-phase case, using the general theory of electrical machines. Further analysis is performed for all the theoretically possible odd phase numbers and it is shown that the number of machines connectable in series depends on the properties of the phase number. Connection diagrams are illustrated next for some selected phase numbers and vector control, including the inverter reference current generation, is detailed for the multimotor drive system. The main advantages and drawbacks of the concept are discussed and verification is provided by simulation of a nine-phase four-motor drive system.     

Electrical characterization of germanium p-channel MOSFETs

In this letter, we report germanium (Ge) p-channel MOSFETs with a thin gate stack of Ge oxynitride and low-temperature oxide (LTO) on bulk Ge substrate without a silicon (Si) cap layer. The fabricated devices show 2 /spl times/ higher transconductance and /spl sim/ 40% hole mobility enhancement over the Si control with a thermal SiO/sub 2/ gate dielectric, as well as the excellent subthreshold characteristics. For the first time, we demonstrate Ge MOSFETs with less than 100-mV/dec subthreshold slope.     

Implementing a bespoke supply chain management system to deliver tangible benefits

Companies often focus efforts to improve business efficiencies on internal systems and significant benefits can be achieved by so doing. However, the magnitude of the realised benefit is restricted if only processes within the organisation are targeted for improvement. This paper describes the implementation of a bespoke web-based supply chain management system/online collaboration system. The main drivers behind the development of the system were late deliveries from the supplier and also sporadic and inaccurate delivery schedule information from the supplier. The implementation approach is discussed along with the problems that were encountered en route and the measures that were undertaken to ensure that implementation was successful. The importance of metrics is stressed, as these are essential if any improvements are to be quantified. The metrics enable justification of such projects in financial terms which is compounded by the ‘soft’ benefits that result from the use of such systems.     

Tool selection for optimal part production: a Lagrangian relaxation approach

This paper extends previous work on implementation problems associated with a flexible system that produces flat sheet-metal parts with interior holes. The paper makes four main contributions. First, we formulate the problem of selecting tooling and design standards to minimize the cost of producing parts as an optimization model. Second, we develop a projected subgradient algorithm for the Lagrangian relaxation of the problem by using the model's special structure to develop relationships between the Lagrangian multipliers. Third, we demonstrate that the algorithm produces close to optimal solutions (duality gap less than 2%) very quickly on a number of problems derived using a substantial data set obtained from a Chicago area firm. Fourth, an important variant of the traditional repair kit problem is shown to be a special case of the tool selection problem.     

High-voltage-activated calcium currents in neurons acutely isolated from the ventrobasal nucleus of the rat thalamus

We studied the high-voltage-activated (HVA) calcium currents in cells isolated from the ventrobasal nucleus of the rat thalamus with the use of the whole cell patch-clamp technique. Low-voltage-activated current was inactivated by the use of long voltage steps or 100-ms prepulses to -20 mV. We used channel blocking agents to characterize the currents that make up the HVA current. The dihydropyridine (DHP) antagonist nimodipine (5 microM) reversibly blocked 33 +/- 1% (mean +/- SE), and omega-conotoxin GVIA (1 microM) irreversibly blocked 25 +/- 5%. The current resistant to DHPs and omega-conotoxin GVIA was inhibited almost completely by omega-conotoxin MVIIC (90 +/- 5% at 3-5 microM) and was partially inhibited by omega-agatoxin IVA (54 +/- 4% block at 1 microM). We conclude that there are at least four main HVA currents in thalamic neurons: N current, L current, and two omega-conotoxin MVIIC-sensitive currents that differ in their sensitivity to omega-agatoxin IVA. We also examined modulation of HVA currents by strong depolarization and by G protein activation. Long (approximately 1 s), strong depolarizations elicited large, slowly deactivating tail currents, which were sensitive to DHP antagonists. With guanosine 5'-0-(3-thiotriphosphate) (GTP-gamma-S) in the intracellular solution, brief (approximately 20 ms), strong depolarization produced a voltage-dependent facilitation of the current (44 +/- 5%), compared with cells with GTP (22 +/- 7%) or guanosine 5'-O-(2-thiodiphosphate) (7 +/- 4%). However, the HVA current was inhibited only weakly by 100 microM acetylcholine (8 +/- 4%). Effects of the gamma-aminobutyric acid-B agonist baclofen were variable (3-39% inhibition, n = 12, at 10-50 microM).