Lightpath communications: an approach to high bandwidth opticalWAN's

An architectural approach that meets high bandwidth requirements by introducing a communication architecture based on lightpaths, optical transmission paths in the network, is introduced. Since lightpaths form the building block of the proposed architecture, its performance hinges on their efficient establishment and management. It is shown that although the problem of optimally establishing lightpaths is NP-complete, simple heuristics provide near optimal substitutes for several of the basic problems motivated by a lightpath-based architecture     

Fine-crack mechanics in fatigue calculations. Part 1. Fatigue resistance in smooth steel specimens in tension-compression

In this first part, the failure of smooth specimens in tension-compression is examined from the viewpoint of fine-crack mechanics, which has some detailed features different from those of traditional crack mechanics. An expression is given for the equivalent J integral for the stress intensity coefficient. Allowance is made for the effects of crack width on the growth rate in elastic and elastoplastic deformation. __________ Translated from Khimicheskoe i Neftegazovoe Mashinostroenie, No. 5, pp. 45–48, May, 2006.     

SYNTHESIS OF CHEMICAL REACTION PATHS: ECONOMIC AND SPECIFICATION CONSTRAINTS

The synthesis of alternative reaction paths leading to a desired chemical has received increasing attention in the recent past. A procedure to develop new reaction schemes in a systematic manner was reviewed by the authors ( [ 1 -3] ). The algorithm presented in these earlier papers implied the generation of an infinite number of reaction paths. The thermodynamic feasibility is a preliminary screening which reduces the number of chemical production schemes. Further screening is necessary, taking into account considerations which are related to economics, processing, safety and so on. Some constraints related with role specification, gross added value and demand/supply requirements are analysed in this paper. Examples illustrate the application of the screening procedure, showing that the addition of a few constraints results in a dramatic decrease of alternative reaction paths.     

Dynamic response and safety assessment of a batch process on cooling breakdown

Cooling breakdown in highly exothermic reaction processes may lead to runaway. The sensitivity and the safety assessment of a batch process on cooling breakdown are studied. The dependence of the minimum cooling time and the maximum allowable time of cooling breakdown for safe operation on the process parameters is investigated.     

Lyapunov-based control for switched power converters

Beginning with fundamental properties such as passivity or incremental passivity of the network elements comprised by a switched power converter, the nominal open-loop operation of a broad class of such converters is shown to be stable in the large via a Lyapunov argument. The obtained Lyapunov function is then shown to be useful for designing globally stabilizing controls that include adaptive schemes for handling uncertain nominal parameters. Numerical simulations illustrate the application of this control approach in DC-DC converters     

MOVPE grown Ga/sub 0.6/In/sub 0.4/Sb photodiodes for 2.55 mu m detection

Photodiodes with a long-wavelength cutoff extending out of 2.9 mu m have been fabricated from MOVPE-grown Ga/sub 0.6/In/sub 0.4/Sb homojunctions. These mesa devices without any passivation or antireflecting coating exhibit a peak efficiency as high as 43% at 2.60 mu m.<>     

Relative neighborhood graphs and their relatives

Results of neighborhood graphs are surveyed. Properties, bounds on the size, algorithms, and variants of the neighborhood graphs are discussed. Numerous applications including computational morphology, spatial analysis, pattern classification, and databases for computer vision are described