Self-Propagating High-Temperature Synthesis of Cerium Chromite Substituted with Alkaline-Earth Metals

Cerium chromites, non-substituted and substituted with alkali-earth metals, are synthesized in the self-propagating high-temperature synthesis mode using solid interaction oxidizes. The characteristic temperatures and specifics of interaction between the components are determined for all systems considered. The structural and physicochemical parameters, including the spectroscopic characteristics of the synthesis products depending on the alkaline-earth metal substituent and the degree of substitution, are investigated.     

Toward a free-space parallel optoelectronic computer: a 300-MHz optoelectronic counter using holographic interconnects

We built and tested one of the key components of a free-space holographically interconnected stored-program optoelectronic computer: a counter. The counter is constructed with 1-ns-latency optoelectronic NOR gates and is interconnected with holographic optical elements. Two synchronization methods were also demonstrated: the gate-and-strobe method and the time-of-flight method. These counters represent prototypical optoelectronic finite-state controllers. They were developed to demonstrate the feasibility of providing optoelectronic controllers for optoelectronic processors.     

Terahertz radiation generation in multilayer quantum-cascade heterostructures

I–V and radiative characteristics of multilayer quantum-cascade GaAs/AlGaAs heterostructures with a double metal waveguide are investigated. The I–V characteristics typical of the quantum-cascade lasers are seen. The observed threshold-intensity growth and narrow radiation spectrum are characteristic of laser generation. The measured radiation frequency was found to be about 3 THz, which coincides with the calculated value. Thus, fully domestic terahertz quantum-cascade lasers are demonstrated for the first time.     

Graphene As a Sensitizing Additive to High-Energy Cobalt Salt for Enhanced Initiation by a High-Current Electron Beam

We have studied the influence of graphene additives on the initiation of high-energy cobalt salt by a high-current electron beam of nanosecond duration. The high-energy composite was prepared by ultrasonic mixing of 80 wt% cobalt amminate (NCP) and 20 wt % graphene. It is established that the use of graphene as a sensitizing additive in a high-energy composite decreases the necessary energy parameters of the initiating electron beam and increases the energy characteristics and combustion rate of high-energy materials.     

Density of turbulence-induced phase dislocations

Under certain conditions, light-wave propagation through turbulent media causes a specific type of phase distortion: so-called phase dislocations. A salient feature of phase dislocations is an appearance of zones where the phase turns out to be a multivalued function of coordinates. The problem of turbulence-induced phase dislocations is considered. Both a theoretical treatment and simulations based on the numerical solution of a parabolic equation are used for estimation of the dislocation density. Various turbulence conditions, ranging from weak to very strong ones, are considered as well as the dependences on wavelength, and the inner scales of turbulence are presented. An empirical formula for the dislocation density suitable for a wide range of turbulent and propagation conditions is derived. The results obtained can be useful for both atmospheric and adaptive optics.     

Improvement of copper–molybdenum ore beneficiation using a combined flotation and biohydrometallurgy method

The authors present the results of analysis of material composition and experimental investigations of acid and biohydrometallurgical leaching of middlings on grain size, pH level, leaching process duration, temperature and slurry density. The rational parameters of flotation and acid-bacterial leaching of middlings providing an efficient release of valuable components from mineral complexes and recovery to flotation concentrate and leaching solution have been determined. A combined flowsheet and a beneficiation process for bulk flotation middlings of copper–molybdenum ore have been suggested, which include middlings grinding, sulfide minerals flotation, bacterial leaching of sulfide flotation tailings, liquid-phase extraction of dissolved copper and electrolysis of re-extraction eluates. The suggested combined method of cleaning of middlings of copper–molybdenum ores beneficiation provides the total copper recovery increase by 0.8% with a reduction of the cost price of saleable material by 0.5%.     

Massively Parallel Computation Using Graphics Processors with Application to Optimal Experimentation in Dynamic Control

The rapid growth in the performance of graphics hardware, coupled with recent improvements in its programmability has lead to its adoption in many non-graphics applications, including a wide variety of scientific computing fields. At the same time, a number of important dynamic optimal policy problems in economics are athirst of computing power to help overcome dual curses of complexity and dimensionality. We investigate if computational economics may benefit from new tools on a case study of imperfect information dynamic programming problem with learning and experimentation trade-off, that is, a choice between controlling the policy target and learning system parameters. Specifically, we use a model of active learning and control of a linear autoregression with the unknown slope that appeared in a variety of macroeconomic policy and other contexts. The endogeneity of posterior beliefs makes the problem difficult in that the value function need not be convex and the policy function need not be continuous. This complication makes the problem a suitable target for massively-parallel computation using graphics processors (GPUs). Our findings are cautiously optimistic in that the new tools let us easily achieve a factor of 15 performance gain relative to an implementation targeting single-core processors. Further gains up to a factor of 26 are also achievable but lie behind a learning and experimentation barrier of their own. Drawing upon experience with CUDA programming architecture and GPUs provides general lessons on how to best exploit future trends in parallel computation in economics.     

State Primary Standards in the Area of Radiometry of Ultraviolet Radiation

The present article describes the system used for assurance of the uniformity of measurements of the characteristics of ultraviolet radiation in the wavelength band 0.03–0.40 μm for radiation sources and receivers based on the State Primary Standards of the unit of spectral density of radiance as well as the unit of radiant flux and unit of irradiance. __________ Translated from Izmeritel'naya Tekhnika, No. 11, pp. 17–20, November, 2005.