Development of a novel image intensifier of an amplifiedmetal-oxide semiconductor imager overlaid with electron-bombardedamorphous silicon

We developed a novel image intensifier (II) of an amplified metal-oxide-semiconductor (MOS) imager (AMI) overlaid with electron-bombarded (EB) amorphous silicon (a-Si). The electron bombardment gain (EB gain) was 1500 at an accelerating voltage of 10 kV. Since the multiplication process was free from a phosphorescent screen and a coupling fiber plate as in the conventional II, the resolution was high and the picture quality was good and free from granularity noises, white spots, lag and sticking. As for fatigue of X-ray irradiation, the contrasts of a vertical stripe (Smear) are not detectable and damaged areas in AMI are weak whereas both of those in charge-coupled devices (CCDs) are strong     

Development of an epileptic seizure prediction algorithm using R–R intervals with self-attentive autoencoder

Epilepsy is a neurological disorder that may affect the autonomic nervous system (ANS) from 15 to 20 min before seizure onset, and disturbances of ANS affect R–R intervals (RRI) on an electrocardiogram (ECG). This study aims to develop a machine learning algorithm for predicting focal epileptic seizures by monitoring R–R interval (RRI) data in real time. The developed algorithm adopts a self-attentive autoencoder (SA-AE), which is a neural network for time-series data. The results of applying the developed seizure prediction algorithm to clinical data demonstrated that it functioned well in most patients; however, false positives (FPs) occurred in specific participants. In a future work, we will investigate the causes of FPs and optimize the developing seizure prediction algorithm to further improve performance using newly added clinical data.

     

Using ontology to improve precision of terminology extraction from documents

In this paper, we proposed a new approach using ontology to improve precision of terminology extraction from documents. Firstly, a linguistic method was used to extract the terminological patterns from documents. Then, similarity measures within the framework of ontology were employed to rank the semantic dependency of the noun words in a pattern. Finally, the patterns at a predefined proportion according to their semantic dependencies were retained and regarded as terminologies. Experiments on Retuers-21578 corpus has shown that WordNet ontology, that we adopted for the task of extracting terminologies from English documents, can improve the precision of classical linguistic method on terminology extraction significantly.     

X-ray absorption fine structure combined with fluorescence spectrometry for monitoring trace amounts of lead adsorption in the environmental conditions

The local structure of trace amounts of lead in an adsorbent matrix that contains a high concentration of iron and magnesium (Mg6Fe2(OH)16(CO3) x 3H2O) was successfully monitored by means of X-ray absorption fine structure spectroscopy combined with fluorescence spectrometry. A eutectic mixture of PbCO3 and Pb(OH)2 coagulated when Pb2+ was adsorbed from a 1.0 ppm aqueous solution, and in contrast, the major species was ion-exchanged Pb2+ in the case of adsorption from a 100 ppb aqueous solution. The difference was ascribed to the balance between the precipitation equilibrium for coagulation and the rate of the ion exchange reaction with surface hydroxyl groups.     

Effect of applied voltage frequency on swarming pulsive microdischarges in closed voids

The extinction of the partial discharge (PD) pulse has frequently been observed in an epoxy specimen with a closed void during voltage endurance tests using a CIGRE Method-II electrode. The individual discharge pulse becomes so small that the discharges cannot be detected by conventional pulse detection methods. Such discharges are known as “swarming pulsive microdischarges” (SPMD). In this paper, the SPMD characteristics are investigated by varying the frequency of the applied voltage from 0.1 to 240 Hz. As a result, the SPMD are found to occur less frequently as the frequency is lowered. To seek this cause, one-shot voltages were applied repeatedly at constant intervals. By varying the interval from 0.02 to 100 s, the PD off an electrically aged specimen was measured. It was revealed that the discharge magnitude increases as the interval becomes longer. The onset of SPMD was found to depend on the preceding discharge. The results explain the reason why swarming is harder to occur at lower frequency with a longer discharge interval. Hence, in the conventional pulse detection, it is useful to employ the very low frequency for diagnosis of machine insulation containing enclosed voids.     

Identifying rotation and oscillation in surface tension measurement using an oscillating droplet method

We proposed a new approach to identify the frequencies of droplet rotation and m=±2 oscillation that degrade the accuracy of surface tension measurement by an oscillating droplet method. Frequencies of droplet rotation and m=±2 oscillation can be identified by a phase unwrapping analysis of time dependence of the deflection angle for the maximum diameter of the droplet image observed from above. The present method was validated, using test data with given frequencies. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(7): 421–430, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20214     

Rapid erasing of wettability patterns based on TiO2-PDMS composite films

TiO₂-polydimethylsiloxane (TiO₂-PDMS) composite films are prepared using the sol–gel method from a Ti(OBu)₄–benzoylacetone solution containing PDMS. The prepared films are cured by irradiation with ultraviolet (UV) light. Structural changes in the films after UV irradiation are confirmed by UV–vis absorption experiments, which show that an absorption band characteristic of the benzoylacetonate chelate rings disappears. This finding is ascribed to structural changes associated with the dissociation of the chelate rings. The IR spectra of the thin films exhibit a broad absorption band after UV irradiation, indicating that a Ti–O–Ti network forms in the thin film. Contact angles are measured for the TiO₂-PDMS thin films, showing wettability conversion from hydrophobic to superhydrophilic states by irradiation with oxygen plasma for 1 s. This phenomenon is explained by XPS experiments which reveal that the number of carbon atoms decreases, whereas the number of oxygen atoms increases on the surface of the TiO₂-PDMS composite films. Finally, hydrophobic–superhydrophilic patterns are fabricated based on a patterned TiO₂-PDMS composite film. The film displays a rapid change to superhydrophilicity over the whole film surface upon plasma irradiation for 1 s, which means that the wettability patterns are rapidly erasable.     

A new flame retardant synthetic fiber made by an emulsion spinning process

Emulsion spinning has been discussed as a fiber forming process for a long time. At present, however, there are only a few matrix fibers commercially produced in the world. A matrix fiber composed of polyvinyl alcohol and polyvinyl chloride shows excellent flame retardancy which never goes out either by laundering or by dry cleaning and extremely low toxicity of fumes even when forced to burn. This matrix fiber is being used for home furnishings, apparel and industrial fabrics. The coming into force of regulations on children's sleepwear, carpenting, mattresses and blankets in the USA provides this fiber with a great opportunity to open a market into those fields. It has other features including a soft textural feel, moderate moisture regain and abrasion resistance. Special types of this fiber can be vacuum formed by the same manner that is used for thermoplastics molding.     

Measurement of Rising R-Curve Behavior in Toughened Silicon Nitride by Stable Crack Propagation in Bending

A simple procedure for measuring the R -curve properties of ceramics by a stable fracture test in three-point bending is described. As a typical case, data are displayed for a Si₃N₄ material toughened by the presence of acicular grains in situ grown during the sintering process. The fracture mechanics specimen was a single-edge double-notched beam (SEDNB), whose notch was sharpened to a radius of <10 μm in order to reduce the amount of elastic energy stored at its root prior to crack extension. Furthermore, a stabilizer, specially designed for the bending geometry, was used to control crack stability. During stable extension, the crack could be easily arrested at selected locations of the load-displacement curve, the load quickly released, and the stable crack extension directly measured by the die-penetration technique. The crack resistance, K _R, of the material was calculated from the measured crack extent and the onset load value before unloading. This method enabled us to precisely monitor the critical load value at which the load-displacement curve deviated from linear behavior, as well as crack extensions from a few tens of micrometers to about 1 mm. As an application of this method, the fracture resistance of a Si₃N₄ material with rising R -curve behavior was measured and found to increase from about 5.5 to 9.0 MPaμm^1/2 within a 0.8-mm extension.     

Empirical values for growth-induced anisotropy energy coefficient for designing garnet LPE films

Growth-induced anisotropy energy coefficients and their super-cooling temperature dependence, both attributed to rare-earth ion-pairs, Kⁱ_j, and αⁱ_j, are obtained by analyzing the relationship between growth temperature dependence of uniaxial anisotropy energy, K_u, and garnet compositions. Regression processes were used for analysis. Better agreements are obtained when the newly obtained Kⁱ_j and αⁱ_j values are applied to estimate growth-induced anisotropy energy for 24 garnet compositions. The ratio of calculated growth-induced anisotropy energy values to observed values is 0.98 ± 0.12, when newly obtained Kⁱ_j and αⁱ_j values are used in place of Eschenfelder's Kⁱ_j values (0.85 ± 0.24). Appropriate melt compositions, to obtain LPE garnet films with bubble properties which meet device requirements, are easily given by computer simulation using the newly obtained values.