Nature of scatter of fracture toughness in static loading

The previously proposed model of unstable fatigue crack growth is used to explain a large (in comparison with other mechanical characteristics) scatter of static fracture toughness for 15Kh2MFA and 15Kh2NMFA steels at temperatures below the tactile-brittle transition temperature. The results show that for the materials for which K_fc ¹ < K_Ic the critical stress intensity factor K_Ic depends on the specific energy of inelastic strain W at the tip of the initial fatigue crack in its formation stage. The value of W is a function of the number of load cycles (in the conditions with a constant range of the stress intensity factor K) as a result of irregular fatigue crack growth. Here K_fc ¹ is the minimum cyclic fracture toughness. A method is proposed of evaluating the minimum fracture toughness of the material in static loading based on inspection of the process of irregular fatigue crack growth in the stage of crack initiation.Translated from Problemy Prochnosti, No. 2, pp. 10–16, February, 1990.     

Classes of conjugate elements of the unitriangular group

The paper examines the classes of conjugate elements of the unitriangular group. It is shown that for sufficiently large n the problem of describing the classes of conjugate elements of the group G includes the problem of unitriangular similarity of pairs of matrices. Effective algorithms are constructed for enumeration of classes of conjugate elements and their elements. Representatives of the classes of conjugate elements of the group G with n9 are obtained by computer.Translated from Kibernetika, No. 1, pp. 40–48, January–February, 1990.     

Filter materials for fine cleaning based on metal fibers

Conclusions Permeable materials based on metallic fibers with porous layers sprayed on by the detonation gas method, in tangential filtering of media with ferromagnetic and abrasive impurities ensure fineness of cleaning 1–2 m with comparatively low hydraulic resistance. The application of a magnetic field to material with sprayed-on layer of magnetic alloy made it possible to increase permeability to ferromagnetic particles by a factor of more than 1.5.Translated from Poroshkovaya Metallurgiya, No. 1(325), pp. 77–80, January, 1990.     

Composition of acid tars from production of oils

Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 2, pp. 32–35, February, 1990.     

Waste products from the butane-butylene fraction as raw material for the production of methyl-tert-butyl ether

Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 8, pp. 7–8, August, 1990.     

HAR-sEMG: A Dataset for Human Activity Recognition on Lower-Limb sEMG

Knowledge and Information Systems - In the past decade, human activity recognition (HAR) has grown in popularity due to its applications in security and entertainment. As recent years have...     

Feasibility of the indirect determination of blast-induced rock movement based on three new hybrid intelligent models

Engineering with Computers - The indirect and accurate determination of blast-induced rock movement has important significance in the reduction of ore loss and dilution and in the protection of...     

Differential Evolution Algorithm Based Self-adaptive Control Strategy for Fed-batch Cultivation of Yeast

In the fed-batch cultivation of Saccharomyces cerevisiae, excessive glucose addition leads to increased ethanol accumulation, which will reduce the efficiency of glucose utilization and inhibit product synthesis. Insufficient glucose addition limits cell growth. To properly regulate glucose feed, a different evolution algorithm based on self-adaptive control strategy was proposed, consisting of three modules (PID, system identification and parameter optimization). Performance of the proposed and conventional PID controllers was validated and compared in simulated and experimental cultivations. In the simulation, cultivation with the self-adaptive control strategy had a more stable glucose feed rate and concentration, more stable ethanol concentration around the set-point (1.0 g•L^-1), and final biomass concentration of 34.5 g-DCW•L^-1, 29.2% higher than that with a conventional PID control strategy. In the experiment, the cultivation with the self-adaptive control strategy also had more stable glucose and ethanol concentrations, as well as a final biomass concentration that was 37.4% higher than that using the conventional strategy.     

Two-Stage Method for Grouping News with Similar Topics

Programming and Computer Software - This paper is devoted to event detection as part of news stream analysis. An event is regarded as a group of news texts dedicated to one real-world fact or...