Method for the Microwave Measurement of Carrier Lifetime in Lightly Doped Silicon Ingots

A further investigation is conducted into a new microwave method for evaluating bulk lifetime in silicon ingots     

Optimal and Admissible Programs of Credit Control

The study of optimal credit policy of a developing enterprise was continued with the aim of establishing and analyzing the finite formulas for the final boundary problem of the maximum-principle procedure. Advisability of the pulse crediting as opposed to the continuous crediting and no-credit development, as well as the advantages of the optimal relay payment of debt as compared with the admissible uniform payment were estimated from the point of view of enterprise. The qualitative features stemming from the nonlinearity of the enterprise production function were discussed. Considerations on managing credits in an unstable economic environment were presented.     

Status of Work on the VÉPP-5 Injection Complex

The VÉPP-5 injection complex under construction at the Institute of Nuclear Physics of the Siberian Branch of the Russian Academy of Sciences is a powerful source of intense electron and positron bunches at 510 MeV, which covers all needs of the electron–positron colliding beam setups currently operating and under construction at the Institute of Nuclear Physics. The complex includes a 285 MeV linear electron accelerator, a 510 MeV linear positron accelerator, and an accumulator–cooler with beam injection and ejection channels. Intense work on the design, assembly, and tuning of the linear electron accelerator has been conducted in the last 2 yr. As a result, by August 2002 the linear electron accelerator was put into operation with all standard subsystems. By this time, the isochronous achromatic turning of the electron beam, a system for converting electrons into positrons, and the first accelerating structure of the linear positron accelerator were assembled and put into operation. All this made it possible to accelerate the positron beam up to 75 MeV. Preliminary results of tests of the linear accelerators are presented.     

Influence of preliminary cyclic plastic deformation on crack resistance

The influence of preliminary (before crack origin) cyclic plastic deformation by tension-compression (R = _min/_max = –1 on the brittle fracture resistance of 15Kh2MFA heat resistant steel in two conditions was investigated. The preliminary loading was done at 293 K and the fracture at 123 and 293 K. It was established that in the case of relatively short preliminary deformation the change in static fracture toughness is caused by a change in yield strength as the result of the Bauschinger effect. However, with an increase in cyclic deformation the total irreversibly dispersed specific energy of inelastic deformation and the structural changes in the material are the determining factor. A physically based method is proposed for prediction of the influence of preliminary cyclic plastic deformation on the brittle fracture resistance of cyclically softening steels.Institute of Problems of Strength of the Academy of Sciences of the Ukrainian SSR, Kiev. Leningrad. Translated from Problemy Prochnosti, No. 11, pp. 14–20, November, 1989.     

New generation of boiling-water-reactor nuclear power plants of increased safety

Scientific-Research Construction Institute of Power Engineering. Russian Scientific Center Kurchatov Institute. Special Design Office of Industrial Organization Izhorskii Plant. All-Union Scientific-Research and Design Institute of Power Engineering Scientific-Industrial Organization. Translated from Atomnaya Énergiya, Vol. 73, No. 1, pp. 13–19, July, 1992.     

Change in molecular weight characteristics of an aromatic copolyamide during the polycondensation process

Conclusions The change in molecular weight characteristics and in viscosimetric data during the synthesis process of an aromatic copolyamide has been analyzed. It has been found that, with rise in the degree of completion of the reaction, at definite molecular weight values the dynamic viscosity rises sharply, which indicates the presence of a significant structural component of this system.The effect of polymer molecular weight on fibre physicomechanical properties has been shown. An increase in fibre strength has been noted on increase in molecular weight from 5400 to 7300. The impairment in physicomechanical properties on further increase in polymer molecular weight is connected with difficulties in processing the strongly structured spinning solutions. Processing polymer with a high molecular weight, and, as a consequence, with an elevated dynamic viscosity requires new approaches both to spinning conditions and, possibly, also to synthesis conditions.Translated from Khimicheskie Volokna, No. 2, pp. 29–30, March–April, 1989.     

Investigation of fibres based on rigid-chain polyamides by the wide-line nmr and ultrasonic acoustics

Conclusions -- A dependence of the second moment of the NMR line on the angle between the fibre axis and the magnetic field has been given; the structural coefficient C ₀, C ₂, and C ₄ have been calculated for fibres based on poly-p-phenyleneterephthalamide and poly-p-benzamide at temperatures of –196 and +20°C and for Kevlar-49, from –196 to +400°C.-- The intramolecular structural coefficients C ₀ ^im, C ₂ ^im, and C ₄ ^im have been calculated theoretically, and the orientation parameters and and the acoustic orientation factor f have been obtained, values for which indicate a high degree of orientation of the macromolecules in fibres.-- The smaller values of the second moment of the NMR line for PABI as compared with fibres based on PPTA in the temperature region 250–380°C indicate a more mobile structure for the PABI.-- In the range from –196 to +20°C thermal action leads to a more important change in the coefficient C ₀ for Kevlar-29 and Kevlar-49 as compared with PABI; this is apparently connected with thermal expansion in planes having a predominant concentration of van der Waals bonds for Kevlar-29 and Kevlar-49.Translated from Khimicheskie Volokna, No. 4, pp. 23–26, July–August, 1990.     

Innovation Efficiency Range Estimates by Balance Models

The results of work on creation of an original formalized method for estimation of the economic efficiency of the know-how for selection of the directions for the state investments from the balance models under uncertainty were compactly presented.     

Optimizing prior prediction accuracy for disturbances in guaranteed control problems

We consider and formalize the problem of finding optimal accuracy for prior prediction of disturbances in guaranteed planning problems under the assumption that there exist ready algorithms for processing observations able to increase prediction quality at some significant added costs. We analyze the general qualitative scheme of this problem and find analytic dependencies of optimal prediction quality for an illustrative problem of delivery planning. With the example of this problem, we show how useful it is to establish connections between different components in the disturbance vector. We propose a scheme of step-by-step increase in prediction accuracy that does not require prior knowledge of the prediction costs function.