Computational and Theoretical Studies of Mass‐Spectrometric Measurements of the Comet Halley Dust Composition in Vega Experiments

Results of computational and theoretical studies are presented. A formulation of the problem is given and approaches to its solution are described. Brief information is given on the models, difference methods, and software designed or adapted to perform direct numerical modeling of massspectrometric measurements of cometary dust on PUMA instruments. The results of a number of computational experiments are presented.     

Checking of combinational circuits basing on modification sum codes

Organization of functional checking of combinational circuits based on application of modified sum codes is studied. These codes refer to classes of codes with weighted digits and weighted carriers. Properties of codes and techniques for realization of check-out equipment are defined.     

Structure and Properties of Iron Piston Rings Manufactured by Continuous Cyclic Casting

The microstructure and mechanical and tribological properties of metal of piston rings produced from preforms cast into dry sand-clay molds by the method of continuous cyclic casting are described. The dislocation structure and chemical composition of fine surface layers that appear under friction are studied by x-ray diffraction and spectral analysis. It is shown that chemical elements migrate from the metallic matrix of the rings into surface layers plastically deformed by friction. The advantages of continuous cyclic casting in the production of diesel piston rings are analyzed.     

Logic Complement, a New Method of Checking the Combinational Circuits

A new method of functional checking of combinational circuits by the logic complement of the output function was proposed. A self-testing checker based on the 1-out-of-3 code was described. Results of experimental studies of the standard examples of the MCNC system were presented.     

Correction of Statical Properties of Nonlinear Dynamic Systems

A correction method is designed for models defining equilibrium states of nonlinear dynamic systems whose equilibrium states are characterized by polynomial nonlinearities.     

Structural anelasticity of NiTi during two-stage martensitic transformation

The two-staged thermoelastic martensitic transformation (TMT) B2→R→B19′ in polycrystalline equiatomic NiTi has been studied by means of measurements of strain amplitude-independent and amplitude-dependent internal friction (ADIF), Young’s modulus and amplitude-dependent modulus defects. The internal friction measurements were performed at a frequency of about 100 kHz, rendering negligible the transient internal friction component and allowing one to investigate the structural internal friction, much less dependent on the external parameters such as the heating/cooling rate or the frequency of vibrations. Attention is focussed on the amplitude-dependent anelasticity. Based on the data obtained, the anelasticity is associated with the dislocations inside the martensitic variants, not with the interfaces or interface dislocations, as is traditionally done. The ADIF and anelastic strain in the R phase have been found to be an order of magnitude higher than in the B19′ martensitic phase. This observation is explained by a much higher density of the dislocations inside the variants of the R phase as compared with that of the B19′ phase.     

Radiography and local microanalysis for detection and examination of actinide-containing microparticles

A procedure was proposed for examination of the spatial microdistribution of fissile actinide isotopes (²³⁵U, ²³⁹Pu) in various environmental objects (soils, bottom sediments, aerosols, colloid material). Complex analysis of natural actinide-containing microparticles involves α-track radiography (ATR) and neutron-induced fission track radiography (NITR), highly sensitive nondestructive methods for determining the spatial microdistribution of α-emitting and fissile actinides, respectively, and scanning electron microscopy with energy-dispersive spectrometry (SEM-EDS) and secondary ion mass spectrometry (SIMS) for local microanalysis of the general elemental and isotope composition of the particles and determination of the morphology and size of the particles. The actinide-containing particles were localized using an SEM microgrid with electrodeposited ²³⁹Pu. Particles characterized by a high concentration of actinides were detected by SEM and SIMS, while those with a low content of actinides, by track radiography followed by fragmentation of the sample for subsequent analysis (γ-ray spectrometry etc.).