On the deuterium quadrupole coupling constant of H-doped Y---Ba---Cu---O systems

The ²H quadrupole coupling constant e²qQ/h and asymmetry parameter η were measured for deuterium-doped Y₂BaCuO₅ (green phase) where x=0.31 and 0.61 in H_xY₂BaCuO₅ and at temperatures of 180, 300 and 360 K. The values are e²qQ/h = 235 ± 20 kHz and η = 0.05 ± 0.05, independent of x and the temperature. These results, together with previously measured quadrupole coupling constants of other hydrogen-doped Y---Ba---Cu---O compounds, are correlated with IR stretching frequencies of these compounds and support the model that the hydrogen forms an O---H bond.     

Ultra-fast hybrid analog-digital computation with convenient simulation-language software

The succession of digital program steps in typical hybrid analog digital computer simulations is so similar to the stepwise solution of differential-equation systems that well-established continuoussystem-simulation languages, and especially interactive digital simulation systems, can serve as excellent hybridcomputer software with little modification. In particular, the block-diagram-oriented DARE II simulation language can control the ultra-fast LOCUST analog computer to produce unprecendented hybrid execution speed while still permitting quite simple programming. Examples include iterative optimization, computation of hybrid-computer Monte Carlo statistics, and digital two-variable function generation in a hybrid-computer loop.     

A Comparative Study of Several Feature Transformation and Learning Methods for Phoneme Classification

This paper examines the applicability of some learning techniques for speech recognition, more precisely, for the classification of phonemes represented by a particular segment model. The methods compared were the IB1 algorithm (TiMBL), ID3 tree learning (C4.5), oblique tree learning (OC1), artificial neural nets (ANN), and Gaussian mixture modeling (GMM), and, as a reference, a hidden Markov model (HMM) recognizer was also trained on the same corpus. Before feeding them into the learners, the segmental features were additionally transformed using either linear discriminant analysis (LDA), principal component analysis (PCA), or independent component analysis (ICA). Each learner was tested with each transformation in order to find the best combination. Furthermore, we experimented with several feature sets, such as filter-bank energies, mel-frequency cepstral coefficients (MFCC), and gravity centers. We found LDA helped all the learners, in several cases quite considerably. PCA was beneficial only for some of the algorithms, and ICA improved the results quite rarely and was bad for certain learning methods. From the learning viewpoint, ANN was the most effective and attained the same results independently of the transformation applied. GMM behaved worse, which shows the advantages of discriminative over generative learning. TiMBL produced reasonable results; C4.5 and OC1 could not compete, no matter what transformation was tried.     

High-speed block-diagram languages for microprocessors and minicomputers in instrumentation,control and simulation

Block-diagram languages implement instrumentation, control and simulation programs in terms of analog-computer-like block diagrams. Block-operators, which range from simple adders to complete real-time controllers and amplitude-distribution analyzers, are assembly-language macros, ROM subroutines or microprograms. Block-diagram languages are readily accepted by engineers, who need not learn assembly language and can still obtain essentially optimal execution speed on small machines. Block-diagram-programmed minicomputers can beat a CDC 6400 using FORTRAN, and microprocessor execution is much more efficient than PL/M. Machine independent block-diagram programs are sorted and cross-translated by optimizing translators, which eliminate redundant memory references. Efficient block-operator macros, subroutines or microprograms are written once and for all by computer specialists, but new operators can be added at will. This paper discusses an optimal minicomputer translator, an interactive microcomputer system using BASIC to generate and test block-diagram programs, hand-translation for small microprocessor programs and some applications.     

Thermomechanical devulcanization of ethylene propylene diene monomer rubber and its application in blends with high-density polyethylene

The recycling of ethylene propylene diene monomer (EPDM) rubber remains a challenge, as its cross-linked structure cannot be broken down reversibly. Devulcanization may offer a breakthrough; however, a 100% decrease in cross-link density (CLD) with no chain degradation has never been reported. In this research, sulfur- and peroxide-cured EPDM rubbers of known compositions were devulcanized on a two-roll mill and in an internal mixer. The CLD of both rubber samples decreased by around 85%, while the sol content of the peroxidic devulcanizate was considerably higher than that of the sulfuric devulcanizate (23% vs. 3%). Horikx's theory revealed that sulfur-cured samples showed excellent selectivity for cross-link scission, while peroxide-cured samples suffered degradation. Uncured, cured, and devulcanized rubber samples were mixed into high-density polyethylene at various compositions. Large EPDM rubber contents impaired the mechanical properties of the blends, indicating insufficient adhesion between the two phases. Compounds containing originally uncured rubber mixtures had the most beneficial mechanical properties.     

Phase-locked ions and foil transparency in the radiation pressure acceleration regime

The transverse expansion of a thin foil accelerated in the RPDA regime can be exploited in order to increase the ion energy and the acceleration efficiency at the expense of decreasing the number of accelerated particles. In the relativistic regime, the ions become phase-locked with respect to the electromagnetic wave. The use of an optimal laser pulse shape makes it possible to keep the expanding foil opaque to the laser radiation. This provides a new approach in order to enhance the energy of laser accelerated ions significantly.     

Hirsch-type indices for characterizing networks

Hirsch-type indices are devised for characterizing networks and network elements. Their actual use is demonstrated on scientometric examples, and the potential value of the concept on a practically unlimited range of networks is suggested.     

Two-dimensional characterization of spatially entangled photon pairs

We characterize the entanglement in position and momentum of photon pairs generated in type-II parametric down-conversion. Coincidence maps of the photon positions in the near-field and far-field planes are observed in two transverse dimensions using scanning fiber probes. We estimate the covariance matrix of an effective two-mode system and apply criteria for entanglement based on covariance matrices to certify space–momentum entanglement. The role of higher-order spatial modes for observing spatial entanglement between the two photons is discussed.