Comparative Assessment of the Effect of Chemical and Radiation Factors on Workers and the General Public Resulting from the Salvaging of Nuclear-Powered Submarines

The results of observations performed over many years are used to make an assessment of the degree to which the concentration of chemical and radioactive substances escaping into the environment during salvaging of nuclear-powered submarines exceeds the admissable norms for workers at the main ship-repair facilities in Russia and for the general public in the surrounding territories. It is shown that the chemical substances are a determining factor in environmental contamination. Their content in the atmosphere and sea water exceeds the admissable norms near sources, on the territory of the enterprises, and (for individual indicators) at populated points. Under these conditions, the concentration of technogenic radionuclides does not exceed the admissable norms and its damaging effect on man is hundreds and thousands of times less than that of chemicals.     

ON AVERAGED DIFFUSION EQUATIONS

Methods of obtaining averaged diffusion equations are considered in case of non-uniform profile of the velocity in a channel. With the flow of Couette as an example, the comparison of exact and approximate solutions (obtained by means of perturbation method) has been carried out. The peculiarities of function of residence time distribution of liquid in the flows with non-uniform velocity field are noted. It is shown that the distribution function moments values including the zero and first moments values would depend on the degree of the velocity profile irregularity, on efficiency of radial mixing in a system as well as on the averaging method. The averaged diffusion equations which have been found by means of perturbation method are the most general of proposed ones at present in the appropriate literature. The Taylor's model and Goldstein's hyperbolic equations are included in said averaged equations as particular cases. The table of the numerical values of first three moments of RTD-function necessary for determining of the model parameters is given. The problems of application of the obtained averaged equation for calculating real chemical apparatuses, e.g. reactors, are discussed.     

Experimental study on a planar capacitative displacement sensor

An experimental study is described on a planar capacitative displacement sensor. It differs from existing models in being simple and giving scope for using film techniques. The sensor is particularly effective in measuring large displacements, e.g., in physics equipment.Translated from Izmeritel'naya Tekhnika, No. 3, pp. 36–37, March, 1995.     

Synthesis of dissipative systems using quadratic differentialforms: part II

For pt.1 see ibid., p.53-69 (2002). The authors discuss several important special cases of the problem solved in Part I. These are: disturbance attenuation and passivation, the full information case, the filtering problem, and the case that the to-be-controlled plant is given in input-state-output representation. An interesting aspect is the notion of full information, which we define in terms of the observability of the to-be-controlled variables from the control variables. When the system is given in state space form, we obtain conditions for the existence of a controller that renders a system dissipative in terms of two coupled algebraic Riccati inequalities. The controller turns out to be a feedback system with a transfer function that is proper, but, in general, not strictly proper. Another issue that we study in this paper is feedback implementability. We find conditions under which, in the context of synthesis of dissipative systems, a controlled behavior can implemented by a feedback controller     

Relative Yield and Period of Individual Groups of Delayed Neutrons in 233U, 235U, and 239Pu Fission by Epithermal Neutrons

The relative yield of delayed neutrons and the half-life of their precursor nuclei in fissioning of ²³³U, ²³⁵U, and ²³⁹Pu by epithermal neutrons are measured on a setup which is based on a KG-2.5 electrostatic accelerator. The experimental samples are irradiated in a polyethylene cube, one face of which is irradiated by a neutron beam consisting of T(p, n)³He neutrons. A procedure is developed for averaging the group parameters of delayed neutrons from different series of measurements, taking account of their correlation. A comparative analysis of the data of this work and in ENDF/BVI in terms of the average half-life of the precursor nuclei of the delayed neutrons and using the dependence of the reactivity on the asymptotic period of the reactor is performed.It is shown that the data of this work agree, to within the uncertainty limits, with the recommended experimental data and differ substantially from the ENDF/BVI data.     

Stabilization of Time-Varying Linear Discrete Interval-Coefficient Control Systems by Phase State Observations

Stabilization of the trajectories of a linear discrete system closed by dynamic feedback under interval uncertainty of the equations of motion and observation is studied. Sufficient conditions of stabilizability are formulated. Results of numerical experiments are given.     

Characterization of charge trapping in submicrometer NMOSFET's bygate capacitance measurements

Trapping of net positive charge at low gate stress voltage, and of net negative charge at high gate stress voltage, is observed through changes in the gate-to-drain capacitance of the stressed junction. These observations can be explained in terms of electron trapping, hole trapping, and generation of acceptor-like interface states located in the upper half of the bandgap. Channel shortening is also observed and found to exhibit a logarithmic time dependence     

Probabilistic reliable dissemination in large-scale systems

The growth of the Internet raises new challenges for the design of distributed systems and applications. In the context of group communication protocols, gossip-based schemes have attracted interest as they are scalable, easy to deploy, and resilient to network and process failures. However, traditional gossip-based protocols have two major drawbacks: 1) they rely on each peer having knowledge of the global membership; and 2) being oblivious to the network topology, they can impose a high load on network links when applied to wide-area settings. In this paper, we provide a theoretical analysis of gossip-based protocols which relates their reliability to key system parameters (the system size, failure rates, and number of gossip targets). The results provide guidelines for the design of practical protocols. In particular, they show how reliability can be maintained while alleviating drawback by: 1) providing each peer with only a small subset of the total membership information and drawback; and 2) organizing members into a hierarchical structure that reflects their proximity according to some network-related metric. We validate the analytical results by simulations and verify that the hierarchical gossip protocol considerably reduces the load on the network compared to the original, non-hierarchical protocol.     

An electrooptic intensity modulator with improved linearity

A highly linear electrooptic modulator has been designed, fabricated, and evaluated. The design of this modulator consists of only a simple modification to the directional coupler. Two-tone testing has demonstrated that, for an optical modulation depth of 30% per channel, the third-order intermodulation distortion is more than 30 dB lower than that of the conventional directional coupler or Mach-Zehnder modulators. This improvement was not observed to be accompanied by any increase in second harmonic distortion. Also included are results of two-tone computer simulations which predict the improvement in linearity of this device for a range of modulation depths.<>