Improvement of regional telecommunications networks

The problems concerning the component improvement of an existing regional telecommunications network, including determination of bottlenecks, redesigning of components, and system expansion by addition of components are discussed. The basic combinatorial models are multicriteria ranking and a multicriteria multiple-choice knapsack problem. The set of requirements (criteria) applied to the system improved comprises reliability, throughput, controllability, and other features. The solution is attained by using the two-stage combinatorial heuristic scheme (the ranking of local designing variants of improvement and the multiple-choice knapsack problem). The ranking procedure is based on the Electre-like version of outranking. The multiple choice knapsack is constructed by means of greedy heuristics. Two variants of improvement of the initial network, namely, a partial redesigning and a full redesigning, are analyzed. The proposed approach is illustrated with the realistic example of a regional (municipal) telecommunications network comprising ten node types.     

Structure and Hardness of Cast Iron after Surface Hardening

Special features of structure formation in the heat-affected zone of roll-foundry iron with flaked or globular graphite due to surface heat treatment by direct electric (plasma) arc are considered. The influence of the parameters of the process on the composition, structure, and properties of the hardened zone is studied. Treatment modes ensuring a structure with enhanced hardness and wear resistance in the surface layer of iron are determined.     

Theoretical study of the kinetics of austenitization in steels with heating by continuous laser radiation

A determination is made of the degree of austenitization taking place with the diffusional displacement of grain boundaries in different regions affected by laser radiation (LRR). The process of the formation of stable austenite is analyzed.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 52, No. 3, pp. 444–449, March, 1987.     

All stability multipliers for repeated MIMO nonlinearities

For block structured monotone or incrementally positive n-dimensional nonlinearities, the largest class of convolution operators (stability multipliers) that preserve positivity is derived. These multipliers can be used in conjunction with positivity and IQC stability criteria to evaluate stability and robustness of MIMO feedback systems.