Determination of the thermal conductivity of amorphous metallic alloys

Two techniques are suggested for identifying the temperature dependence of the thermal conductivity of a new class of materials. The results have been obtained for the metallic glass Co₇₇Fe₄Cr₇Si₈B₄.Institute for the Problems of Mechanical Engineering, Kharkov. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 63, No. 3, pp. 314–320, September, 1992.     

Parameters of hydraulic fracturing and disintegration of impervious rocks while preparing blocks for leaching

Conclusions 1. The maximum water injection pressure for hydrofracturing of Blyava ores was 12.1–12.9 MPa and for hydrodisintegration, 4.5–5.5 MPa. The calculated values of these pressures differ from the experimental ones by 20–25% and 25–36% respectively, which is satisfactory for natural-scale studies.2. The probability of hydrofracturing or hydrodisintegration of the mass depends a great deal on the distance between the packer and the borehole face. It has been demonstrated experimentally that hydrofracturing occurred at a distance of 0.1–0.6 m and only hydrodisintegration was noticed at a distance of 4–10.2 m. These data show that, all other conditions being equal, the packer (interpacker) spacing of the boreholes is of great importance for producing, in practice, some type of hydrodynamic impact on the rock mass.3. Water injection through boreholes into the ore body under conditions of hydrofracturing and hydrodisintegration showed the real possibility of establishing a hydrodynamic link between boreholes at distances of 5 m, 10 m, and greater.4. The technology and equipment developed by the Institute of Mining make it possible to prepare blocks of impervious ores for leaching by employing hydrofracturing and hydrodisintegration of rocks and creating in the block a borehole — slit — borehole system.5. As a result of suffosion of the ore, slime is released intensely from the drainage boreholes, which is typical for hydrofracturing and hydrodisintegration processes and for subsequent fluid injection under pressure. This may be used to augment the performance of the borehole — slit — borehole system.6. If conditions in the mining industry become favorable, it would be advisable to continue the operations, the essential features of which are elucidated in this paper.Translated from Fiziko-tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 5, pp. 100–105, September–October, 1996.     

Clinical and functional evaluation of health status of workers exposed to infrasound, noise and general vibration

The article covers complex evaluation of health state in building industry workers engaged into ferro-concrete production in St. Petersburg. The health state was considered under combined action of infrasound, noise and general vibration. Clinical and functional evaluation included medical examination by doctors, blood biochemistry and CBC, ECG, computer integral rheography, voice audiometry. Data for 62 moulders helped to assess acoustic environment at workplace and to reveal the morbidity structure.     

A terahertz scanning near-field optical microscope with an attenuated total internal reflection module

The first terahertz scanning near-field optical microscope with an attenuated total internal reflection module and a free-electron laser (FEL) as the radiation source was developed. A scanning system with positioning using a confocal sensor with chromatic coding and a surface-subwavelength probe touch sensor were developed and tested. A new technique for sensing the distance between the probe and a conducting surface via corona-discharge current measurement was developed. A specific lock-in system for detection of probe-scattered pulse-periodic radiation, which includes a hot-electron superconducting bolometer and an electronic signal-storage circuit, was developed to operate with the Novosibirsk terahertz FEL. All elements of the microscope were tested, and their working capacity was demonstrated. Experiments on the detection of microscope-probe-scattered terahertz radiation have been initiated.     

Stealthiness of analytical chaotic signals

This paper considers an approach to constructing analytical chaotic sequences with statistical and dynamic characteristics that are close to the white noise characteristics. The notion of stealthiness and its measure were introduced for these sequences. Attractors of constructed sequences and their cross-correlation functions were studied. The results obtained in this paper can be used for enhancing the stealthiness of radio data transmission systems.     

Tribomechanical calculation method of the lateral pressure coefficient for brittle dispersed materials

A calculation procedure is proposed to analyze the lateral pressure coefficient of brittle dispersed materials with account of the joint effect of the interparticle and external (wall or boundary) friction modes The measurement range of this coefficient is defined as the ratio of the interparticle friction coefficient to the external (boundary) friction one.     

Use of BDS statistic to estimate security of a signal obtained by mixing chaotic carrier

Efficiency of using the method of mixing a chaotic carrier to provide signal security in information transmission systems with use of BDS statistic is studied in this work. By means of statistical modeling for a specific example the increase in security by more than four times is demonstrated.