Deadlock-free connection-based adaptive routing with dynamic virtual circuits

Virtual circuits (VCs) can reduce routing overheads with irregular topologies and provide support for a mix of quality of service (QoS) requirements. Information about network loads and traffic patterns may be used during circuit establishment to utilize network resources more efficiently than is practical with packet routing. Most VC schemes are static—each established VC remains unchanged until the connection is no longer needed. In contrast, we propose the dynamic virtual circuit (DVC) mechanism, which enables existing circuits to be quickly torn down in order to free up resources needed for other circuits or to re-establish circuits along routes that are better suited for current network conditions. We propose a deadlock avoidance technique, based on unconstrained routing of DVCs combined with a deadlock-free virtual network. We present a correctness proof for the scheme, describe key aspects of its implementation, and present performance evaluation results that explore its potential benefits.     

An Abstraction Algorithm for the Verification of Level-Sensitive Latch-Based Netlists

High-performance hardware designs often intersperse combinational logic freely between level-sensitive latch layers (wherein each layer is transparent during only one clock phase), rather than utilizing master-slave latch pairs with no combinational logic between. While such designs may generally achieve much faster clock speeds, this design style poses a challenge to verification. In particular, unless the k-phase netlist N is abstracted to a full-cycle register-based netlist N, verification of N requires k times (or greater) as many state variables as would be necessary to obtain equivalent verification of N. We present algorithms to automatically identify and abstract k-phase netlists—i.e., to perform phase abstraction—by selectively eliminating latches. The abstraction is valid for model checking CTL* formulae which reason solely about latches of a single phase. This algorithm has been implemented in the model checker RuleBase, and used to enhance the model checking of IBM's Gigahertz Processor, which would not have been feasible otherwise due to computational constraints. This abstraction has furthermore allowed verification engineers to write properties and environments more efficiently.     

New correlations for fitting multicomponent vapor-liquid equilibria data and prediction of azeotropic behavior

Correlation equations for expressing vapor-liquid equilibria data as a function of liquid composition: the P-X (eqns 4–6), T-X (eqn 7) and Y-X (eqns 14–18), have been tested successfully. On the basis of the new correlations, equations are derived for predicting azeotropic behaviour of multicomponent mixtures and the kind of azeotrope (minimum, maximum and saddle type). Consequently, new ternary azcotropes were predicted. It was found that direct correlation of intensive properties of mixtures and vapor equilibria data is always much more efficient than a correlation based on complete information.     

Correlation of vapor-liquid equilibria in systems showing homoazeotropy or heteroazeotropy using expressions for the total pressure and temperature as direct functions of vapor composition

Correlation equations for the boiling temperature and the total pressure as direct functions of vapor composition have been tested successfully and applied for exploring binary and ternary systems showing homogeneous azeotropy and heteroazeotropy.     

Tautomerism and Ionisation of 6-Thioxopurin-8-Ones. A Contribution to the Behaviour of 6-Thiopurines

The neutral molecules of 6-thioxopurin-8-ones are present in aqueous solution as lactams-thiolactams. However, 6-SH-tautomers may be present in the anions of the 1- and 9-methyl derivatives. The sequence of dissociation of the NH-groups is 1 → 9 → 7. Ionisation of the 9-NH-group is greatly facilitated in the 3-methyl derivatives, leading to pK values of about 5. Protonation of the 3-methyl derivatives takes place predominantly at N-1 with the formation of “fixed”, amidinium-like, cations. In all other members of the series, protonation involves mainly the 8-oxo group. In 3,9-dimethyl derivatives, the NMR signals of both methyl substituents are markedly deshielded. The behavior of 6-thioxopurin-8-ones resembles that of 6-thiopurines and 6-thioxanthines.     

Correlstion and prediction of boiling temperatures and azeotropic conditions in multicomponent systems

Thermodynamic models for multicomponent mixtures were derived and tested successfully for correlation of boiling points and for determining the presenc     

Wave-number symmetries for guided complex waves

The appearance in pairs of complex waves is discussed for an open waveguiding structure. It is shown that the absence of losses in the system requires the simultaneous presence of two complex waves, the wavenumbers of which possess symmetry properties of the conjugate type. These properties still hold if radiation losses occur, and the symmetry disappears only if conduction losses are introduced.     

A photographic study of condensation in the presence of instabilities

A photographic study has been carried out to illustrate the behaviour and appearance of thin films in the presence of instabilities. Such information i     

Leaky-wave analysis of optical periodic couplers

A rigorous analysis of an optical beam coupler of the periodic variety is presented in terms of a leaky-wave formulation. The particular case of a surface wave producing one or two beams, and the partition of the available energy between these beams, are considered.     

Electromagnetic modeling of quantum-well photodetectors containingdiffractive elements

An analytical approach for modeling optical fields in quantum-well infrared photodetectors was developed by using a rigorous solution of the corresponding electromagnetic problem. Its application includes structures having a large number of dielectric layers, which may contain gratings having arbitrary profiles and metal-strip arrays acting as electrodes. By representing the fields inside complex photodetector structures in terms of interconnected transmission-line units, this approach helps considerably to clarify the role of each constituent of the photodetector. Examples involving realistic situations reveal that the presence of metal electrodes may affect the photodetection operation in a large class of grating structures. In particular, we show that the sensitivity of specific photodetector configurations can be enhanced by choosing grating parameters that optimize the overall photodetecting performance