Analysis of performance of fuel elements of the BOR-60 reactor with vibrocompacted uranium-plutonium oxide fuel

Translated from Atomnaya Énergiya, Vol. 66, No. 5, pp. 299–302, May 1989.     

Speaker identification based on adaptive discriminative vector quantisation

A novel adaptive discriminative vector quantisation technique for speaker identification (ADVQSI) is introduced. In the training mode of ADVQSI, for each speaker, the speech feature vector space is divided into a number of subspaces. The feature space segmentation is based on the difference between the probability distribution of the speech feature vectors from each speaker and that from all speakers in the speaker identification (SI) group. Then, an optimal discriminative weight, which represents the subspace's role in SI, is calculated for each subspace of each speaker by employing adaptive techniques. The largest template differences between speakers in the SI group are achieved by using optimal discriminative weights. In the testing mode of ADVQSI, discriminative weighted average vector quantisation (VQ) distortions are used for SI decisions. The performance of ADVQSI is analysed and tested experimentally. The experimental results confirm the performance improvement employing the proposed technique in comparison with existing VQ techniques for SI and recently reported discriminative VQ techniques for SI (DVQSI)     

Reactive electric-discharge sintering of TiN-TiB2

Powder mixtures based on titanium and its dihydrides are sintered by electric discharge in a certain current mode to produce TiN + TiB₂ composites. It is established that the use of tetragonal titanium hydride as the starting material results in the complete synthesis leading to a TiN + TiB₂ composite. The higher shrinkage rate results from the higher purity of titanium dihydride, which, in its turn, increases the partial pressure of hydrogen in the reaction area and the reaction rate. Tetragonal titanium hydride is more preferable than cubic hydride and metal titanium. The microstructure of alloys resulting from the sintering of hydride-based mixtures is more homogenous: it includes equiaxial grains with the mean size of about 1 µm.     

Acute erythroleukemia: evaluation of 48 cases with reference to classification, cell proliferation, cytogenetics, and prognosis

We evaluated 48 archival cases of acute erythroleukemia and divided them into 3 groups: M6a, corresponding to the traditional French-American-British M6 category; M6b, which is pure erythroleukemia; and M6c, in which myeloblasts and pronormoblasts each account for more than 30% of cells by the French-American-British exclusion criteria. No significant differences were noted among the subtypes for ratio of males to females; age; or exposure to toxins, alcohol, or both. However, compared with the patients in the M6a group, patients in the M6b and M6c groups demonstrated a statistically significant increase in cytogenetic aberrations, proliferation markers (proliferating cell nuclear antigen and Ki67), and ringed (type III) sideroblasts. Marked survival differences were noted between the M6a (30.1 +/- 29.5 months) and M6b (3.15 +/- 4.2 months) groups, with patients in the M6c group demonstrating an intermediate prognosis (10.5 +/- 12.7 months). Chemotherapeutic regimens induced remission in all treated patients in the M6a and M6c groups but did not appear to affect the M6b group. However, the patients in the M6c group remained in remission for a significantly shorter period of time than did patients in the M6a group. Overall, survival appeared to depend on the ratio of pronormoblasts to myeloblasts at diagnosis and demonstrated a rapid decline with increasing pronormoblast and decreasing myeloblast counts. We must, therefore, devise chemotherapeutic regimens that target both blastic components of this disease.     

Numerical Shaping Method for Hobbing Tools

A numerical method is proposed for the shaping of tools used in machining complex surfaces with a periodical profile, including screw surfaces. A heuristic approach to Mathcad programming is adopted. The mathematical formulation includes a module generating spatial transformations of the coordinate systems in matrix form. On that basis, a numerical model of a hob profile is constructed. This approach permits single-stage shaping, without determining the profile of the associated helical gear.     

Behavior of heat-resistant alloys and titanium alloys on cutting

The properties of heat-resistant alloys used for the manufacture of compressor blades are analyzed. The optimal cutting speeds for titanium alloys and heat-resistant alloys are determined. The dependence of the plastic strain and chip formation on the cutting speed in the broaching of such alloys is established.     

Thermal stability of the phase composition and structure of hafnium diboride films

The thermal stability of the composition and crystal structure of hafnium diboride films grown by rf magnetron sputtering have been studied by X-ray diffraction and secondary ion mass spectrometry. We have assessed the effect of high-temperature annealing in air on the phase composition and structure of the hafnium diboride films. The results demonstrate that annealing produces a HfO₂ oxide layer on the surface of the HfB₂ film. Raising the annealing temperature from 600 to 1000°C leads to an increase in the thickness of the oxide layer from 100 to 600 nm and to the formation of a multilayer HfB₂-HfO₂ coating.     

Separation of ammonia-containing gas mixtures in a one-compressor multistage membrane apparatus

Separation of the gas mixtures 7.7 vol % nitrogen in ammonia and 5.5% carbon monoxide in ammonia in one-compressor multistage membrane devices with one and two separation steps has been compared. The apparent values of selectivity have been determined for these gas mixtures. Expressions relating the degree of separation to the stage cut and the degree of purification to the product loss have been experimentally obtained. The degree of purification has been shown to increase with the number of stages despite of the fact that the degree of separation at individual stages is lower than in a single membrane module.