Adaptive nonlinear cancellation for high-speed fiber-optic systems

The authors propose techniques for adaptive nonlinear cancellation of intersymbol interference (ISI) in the electrical signal at the receiver in Gb/s lightwave systems and describe several demonstrations of these techniques. Techniques for adjustable nonlinear cancellations are discussed and demonstrations of these techniques using commercially available integrated circuits (ICs) at data rates as high as 1.7 Gb/s are described. Techniques for automatic adjustment are discussed, and a demonstration of adaptive nonlinear cancellation at 450 Mb/s is described. The authors discuss how these techniques can be integrated onto the detector IC for operations at 2.5 Gb/s and higher data rates. These techniques allow a single IC detector with adaptive nonlinear cancellation to be used in long-haul and undersea lightwave systems to optimize the detector threshold and compensate for the ISI     

New wire interface for graded 3-D TLM

A new 3-D graded TLM model for thin radiating wires is presented. The model differs from previous TLM models because the wire is modelled at the interfaces between cells, rather than through the centre of the node. The connection between the TLM symmetrical condensed-node link lines and the line forms a 'wire interface'. The scattering algorithm for the interface and simulation results are given.<>     

Performance of 1700 m2 solar pond operation in arid zone

A 1700 m² solar pond was constructed in the desert of Kuwait where severe weather conditions prevail in all seasons. The paper describes in detail a diffuser design for the gradient establishment, gradient stability, and thermal performance of the pond. The main problem encountered in operating the pond was mixing between the upper zone and the gradient zone, even when the wind speed was as low as 5 m/s. No mixing between the gradient and the lower connective zone was observed. The wind effect was severe in causing mixing even when the upper convective zone increased to 0.90 m.     

Expert system “assistent” for bayes' intellectual measurements of probability characteristics

Translated from Izmeritel'naya Tekhnika, No. 8, pp. 11–14, August, 1992.     

New possibilities of chemical beneficiation of synnirites

Institute of Geology Siberian Branch, Academy of Sciences of the USSR, Novosibirsk. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 1, pp. 106–109, January-February, 1992.     

Numerical modeling of nonsteady transient processes in a sphere with cavity subjected to internal dynamic load

The article suggests a numerical algorithm for investigating shock-wave processes in a hollow sphere with limited thickness subjected to internal dynamic surface loads. On the example of actual boundary conditions the article evaluates the contribution of all groups of elastic waves to the formation of an overall structure of rapidly occurring wave processes within the medium under consideration. The effect of the boundary conditions on the distribution field of the components of displacements, speeds, strains and stresses across the hollow sphere upon multiple passage of stress waves was discovered, and some aspects of the realized numerical algorithm connected with the stability of the scheme were investigated.Translated from Problemy Prochnosti, No. 8, pp. 15–19, August 1992.     

Equalization of a hard-limited slowly-fading multipath signal usinga phase equalizer with time-reversal structure

Describes a low-complexity equalization technique for improving the reliability of portable radio links in the presence of multipath time delay spread. A technique that operates on hard-limited received signals, with only the phase information available, is presented. Suboptimum receivers based on a maximum likelihood estimation criterion are discussed, including a sequence estimator and a decision feedback phase detector. A low-complexity adaptive phase equalizer structure using decision-directed phase tracking is proposed. The equalizer does not require the multiplication operations required in most conventional equalization algorithms. The author also proposes a receiver that includes a time-reversal structure and a joint estimator for optimum timing recovery and equalizer training. The time-reversal structure plays a crucial role in maximizing the compensation capability of the phase equalizer. The combined use of phase equalization and diversity reception is also considered     

Face recognition: combining cognitive psychology and imageengineering

Many cognitive tasks that are easy for humans to perform are proving difficult to emulate in computer systems. Combining the disciplines of psychology and engineering may offer a solution to some of these problems. A connectionist or neural network model of face recognition by humans which incorporates aspects of a model proposed by cognitive psychologists is presented. A comparative set of experiments has been performed using this simulation and human subjects for familiar face recognition. By employing the same stimuli for both humans and the computer model, it is possible to advance not only our understanding of human cognition but also to develop improved automated systems for face recognition     

Gradient interpenetrating polymer networks

The methods of synthesis and properties of gradient interpenetrating polymer networks (IPN) are discussed based on literature and authors' own experimental data. Gradient IPN can be treated as a sequence of an infinite number of layers of IPNs, whose composition and properties vary gradually from the surface to the core of specimens. These are analysed the most important properties of gradient IPNs: temperature transitions, thermodynamic and physico-mechanical characteristics and the main direction of practical application of gradient IPN-based materials.     

Energy method of longevity calculation under an irregular loading. Report 2. Longevity under programmed block loading

A method of calculating longevity to macrocrack development under a programmed loading in the form of a block repeated many times to failure is proposed. Relationships are derived for calculation of longevity under blocks with stepwise variation in stress amplitude, and also blocks assigned by the probability-distribution density of the stress amplitudes and tables of the differential frequency of repetition of peak and average stresses. Consideration of variation in the material's endurance limit under an irregular cyclic loading is demonstrated. It is shown that a specific type of relationships can be derived for the material under investigation with allowance for its kinetic cyclic-strain diagrams. An example of the longevity calculation, which is compared with experimental data for the block loading of steel 40Kh specimens, is cited.Translated from Problemy Prochnosti, No. 8, pp. 3–11, August, 1995.