Resistive and magnetic properties of Y1−x Zr x Ba2Cu3O7−δ and Y1−2x Zr x Eu x Ba2Cu3O7−δ superconductive compounds

The results of X-rays, electrical resistivities and magnetic studies performed on Y_−x Zr _x Ba₂Cu₃O_t7−δ and Y_1−2x Zr _x Eu _x Ba₂Cu₃O_7−δ superconducting compounds, in the temperature range 4.2–500 K and external fields up to 50 kOe are reported. The presence of zirconium decreases the superconducting transition temperatures,T _c. BelowT _c, the hysteresis loops narrow when the zirconium content increases. From the magnetization curves, the critical current densities were determined. A time dependence of the magnetizations of logarithmic form was found. The flux-pinning energy was estimated to beU ≃0.03 eV. Above the transition temperatures, Y_−x Zr _x Ba₂Cu₃O_t7−δ samples show a Pauli-type paramagnetism, while Y_1−2x Zr _x Eu _x Ba₂Cu₃O_7−δ compounds have, in addition, temperature-dependent contributions to the magnetic susceptibilities. The effective europium moments are ∼3.40 μ_B suggesting that the ion is in (+3) valence state.     

Adaptive space-time reduced-length MMSE receiver for interferencesuppression in DS/CDMA

The authors present an adaptive space-time reduced-length minimum mean-squared error (MMSE) receiver to suppress co-channel interference in the near-far environment for an asynchronous direct-sequence code-division multiple-access (DS/CDMA) system. Simulation results show that better bit-error rate and faster and more stable convergence are achieved over the existing full- and reduced-length MMSE receivers     

Engineering design and mechatronics: The schemebuilder project

The paper describes the development of a software design aid for use at the conceptual stage of engineering design. It is intended for use in the design of mechatronic products but has wider potential uses. Early approaches were based on function structures and tables of options and the system that evolved allows the assembly of schemes linked by matching their input and output ports. A database of components is provided which can be accessed via different indexes and the designer can easily create and compare alternative schemes at the concept stage.A bond graph approach is used to define the interconnections between components. This allows correct port matching but also provides for future development such as constraint propagation through the design and links to simulation tools.     

Constructing candidate word lists using acoustically similar wordgroups

A method for identifying a set of candidate words that matches well with a given utterance is discussed. The method uses precomputed groups of acoustically similar words. Given a vocabulary, for each word a short list of words that are acoustically similar to it is computed. These groups are constructed using training utterances recorded by several speakers and used in an isolated utterance recognition system to construct candidate word lists during recognition. Experiments show that the correct word appears on the short list of candidate words constructed during recognition using this scheme over 98% of the time     

Quantitative NMR spectroscopy by matrix pencil methods

The matrix pencil (MP) method, based on the singular value decomposition (SVD), is applied to quantitative NMR spectroscopy. Its relationship to other SVD-based methods is also presented. Simulations and applications are given to demonstrate the capability of superior performance.©1993 John Wiley & Sons Inc     

Resistance of rock to the intrusion of a die near the wall of a hole

Institute of Rock Mechanics, Academy of Sciences of the USSR, Moscow. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 1, pp. 39–44, January-February, 1992.     

Influence of thermomechanical and mechanical processing on the fatigue resistance of VT3-1

The influence of the structure and crystallographic texture of VT3-1 alloy formed by thermomechanical processing of a forging and also of the production factors of subsequent production of a gas turbine engine blade from the forging on the fatigue resistance characteristics was investigated. It was established that the reason for the reduction in fatigue limit and the significant spread in test data is nonuniformity of the structure and texture, both in different forgings and within the same forging, caused by variations in such parameters of thermomechanical processing as the temperature and degree of deformation. The nonuniformity plays a determining role in the reduction in fatigue limit as the result of hydrogen absorption during chemical etching. It was shown that such an effect may be eliminated by degassing vacuum annealing and the general level of fatigue resistance characteristics may be increased as the result of thermomechanical processing of forgings with strict observance of the specified forging temperature.Translated from Problemy Prochnosti, No. 6, pp. 12–19, June, 1992.