The integral experiment on beryllium with D-T neutrons for verification of tritium breeding

A clean benchmark experiment on beryllium was performed with D-T neutrons at the FNS facility of the Japan Atomic Energy Agency. The main objective was to verify the integral data related to the tritium production on lithium isotopes. Tritium production rates, as well as activation reaction rates were measured inside the beryllium assembly that was shaped as a pseudo-cylindrical slab with an area-equivalent diameter of 628 mm and a thickness of 355 mm. Experimental results were analyzed with a three-dimensional Monte Carlo transport code MCNP-4C and FENDL/MC-2.0, JENDL-3.2/3.3 neutron transport libraries. Evaluation of reaction rates was based on the cross section data taken from the JENDL Dosimetry File and ENDF B-VI data libraries. Analysis shows that all calculation combinations (transport and activation cross section libraries) used for evaluation of reaction rates give data that is agreeable with measured values within 10%.     

Characteristics and classification of high-current fault arcs on distribution systems

When a fault occurs on transmission or distribution systems due to lightning or overvoltage, often an arc discharge occurs at the fault point. The arc discharge, which is caused by a fault current, has a high current, high temperature, strong light emission, etc., thus it sometimes causes heavy damages to electric power equipment. The arc discharge is influenced by the conditions around the arcs, i.e., gas, insulation materials, gap length, weather, etc. Also, the arc voltage along the arc column indicates the characteristics of the arc. If the voltage waveforms of the arcs caused by the fault on transmission or distribution systems are classified, it is possible to find the location and the equipment where the fault occurred. In this paper, the arc voltage data in 6-kV class XLPE cables and 6-kV class overhead lines are analyzed and an artificial neural network method is applied to classify the arc voltage waveforms. The results obtained from the six artificial neural networks developed show that the artificial neural network method is effective for classification of arc voltage waveforms if adequate input parameters are selected.     

Distance metric learning for graph structured data

Machine Learning - Graphs are versatile tools for representing structured data. As a result, a variety of machine learning methods have been studied for graph data analysis. Although many such...     

Ion exchange of intercalation compounds from WOP2O7 and intercalation ofn-alkylamines

Ion exchange of Na _x WOP₂O₇ ·nH₂O (x 1.4) prepared from WOP₂O₇ was attempted, using alkaline and alkaline earth ions. The degree of exchange was observed to be >50% at 90° C except for Mg²⁺. The basal spacing of ion-exchanged materials for the hydrated phase were dependent on the number of water molecules in the interlayer spaces, while those for the dehydrated phase increased with the size of ions in the interlayer spaces. The network of water molecules linked by the hydrogen bond in the interlayer spaces seems to determine the basal spacing. By the ion-exchange reaction,n-alkylammonium ions were intercalated into the interlayer spaces of Na _x WOP₂O₇ ·nH₂O (x 1.4) and Sn _x H _y WOP₂O₇ ·nH₂O (2x +y 0.5). In spite of the difference in the charge density of the host layer, a similar arrangement of alkyl chains in the interlayer spaces resulted, and neutral amines were considered to be intercalated as well as ammonium ions. Direct reaction ofn-alkylamine with WOP₂O₇ produced an intercalation compound without reduction of tungsten. The arrangement of the amines in the interlayer spaces is similar to that supposed to the ion-exchanged derivatives when heated at 140° Cin vacuo.     

Hydroxyapatite crystal growth on calcium hydroxyapatite ceramics

Calcium hydroxyapatite (Ca-HAP) ceramics containing tricalcium phosphate (TCP) were soaked in three solutions: phosphate buffer, tris buffer, and simulated body fluid (SBF). Petal-like crystals of Ca-HAP were deposited on the Ca-HAP ceramics when (i) Ca-HAP ceramics contained -TCP, (ii) the soaking solution contained phosphate ion and (iii) the pH of soaking solution was higher than 7.3. These conditions facilitate the presence of HPO ₄ ^2– and Ca²⁺ ions, the latter from dissolution of -TCP. A well-defined X-ray diffraction pattern for the deposited Ca-HAP crystals indicates preferred growth of {002} planes. Slower crystal growth of Ca-HAP was found for SBF (pH=7.5) than in the phosphate buffer, due possibly to the lower phosphate ion content in SBF.     

Thermodynamic Regularities in Perovskite and K2NiF4 Compounds

It has been found that the enthalpy of formation of perovskite compounds, Δ_fH° (ABO₃, B = transition metais), from binary oxides can be well characterized in terms the tolerance factor, t≡(r_A+ r_o)√2 (r_B+ r_o), where r_A and r_B are the radii of A-site ions with 12-coordination and B-site ions with 6-coordination, respectively, and Δ_fH°=−168 + 270(1 − t) kJ·mol⁻¹ for A^IB^VO₃, Δ_fH°=−125 + 1000(1 − t) kJ·mol⁻¹ for A^IIB^IVO₃, and Δ_fH°=− 90 + 720(1 − t) kJ·mol⁻¹ for A^IIIB^IIIO₃. Although the thermodynamic data of K₂NiF₄ compounds are not extensive, a similar regularity can be found when use is made of the radii of A-site ions with 9-coordination for the K₂NiF₄ compounds. These correlations will be quite useful in predicting.     

Development of an anisotropic conductive adhesive film (ACAF) from epoxy resins

A thermoset type anisotropic conductive adhesive film (ACAF), which electrically connects an ITO glass and a flex circuit both having conducting pattersn of less than 100 μm in pitch, has been developed. In this development, bisphenol A and bisphenol F epoxy resins were tested to formulate an ACAF with easy-to-handle tackiness, flexibility, and strenght. A curing agent that gives fast cure and long shelf-life properties to the epoxy resin was also selected. The tensile stress–strain responses of obtained adhesive films were successfully used for determining the formulation. Good aftercure physical properties (electrical and mechanical) were obtained. Durability against high temperature and high humidity were also tested to confirm long-term stability of the conduction of this ACAF. © 1995 John Wiley & Sons, Inc.     

Formation of Small-Sized CdSxSe1-x Crystals in Sol-Gel-Derived SiO2 Glasses

Silica glasses doped with small-sized CdS_x-Se_1-x crystals were prepared by the sol-gel method. Gels synthesized by the hydrolysis of Si(OC₂H₅)₄, in the presence of CdSeO₄ with NH₄SCN dissolved in HNO₃ or NH₄OH, were heated in H₂-N₂ atmosphere. The pH value of solutions for CdSeO⁴ and NH⁴SCN primarily determined the fraction of anions in CdS^xSe^1-x crystals. The anion content in crystals was dependent on the pH value of the solvent and/or heat-treatment temperature, and the sulfur fraction changed from 0.1 to 0.6. The optical absorption spectra were red-shifted as the selenium content and the crystal size increased, and the emission spectra showed a sharp band near the absorption edge position and a broad tail extending into the long wavelength. The optical band gap energies increased reciprocally proportional to the square of the crystal size.     

Ring hydrogenation of naphthalene and 1-naphthol over supported metal catalysts in supercritical carbon dioxide solvent

Catalytic ring hydrogenations of naphthalene and 1-naphthol were studied over several supported metal catalysts in supercritical carbon dioxide solvent at low temperature. Higher concentration of hydrogen in supercritical carbon dioxide and lower reaction temperature were responsible for higher catalyst activity and selectivities to the desired partial ring hydrogenated products as compared with those observed in organic solvent for the same catalyst.