Development of a fast neutron radiography converter using wavelength-shifting fibers

A fluorescent converter for fast neutron radiography (FNR) comprising a scintillator and hydrogen-rich resin has been developed and applied to electronic imaging. The rate of the reaction between fast neutrons and the converter is increased by thickening the converter, but its opaqueness attenuates emitted light photons before they reach its surface. To improve the luminosity of a fluorescent converter for FNR, a novel type of converter was designed in which wavelength-shifting fibers were adopted to transport radiated light to the observation end face. The performance of the converter was compared with that of a polypropylene-based fluorescent converter in an experiment conducted at the fast-neutron-source reactor YAYOI in the University of Tokyo.     

The computer: liberator or jailor of the creative spirit

A discussion of the historical and aesthetic questions raised by the Fine Arts community regarding the uses of the computer by artists, its limitations and its potential. Creating a texture and context for this discussion necessitated the weaving into this discussion the role of technology, science, mathematics, the humanities, and aesthetics in the visual arts.     

Electronic and optical analysis of high-efficiency photovoltaic materials based on a GaN semiconductor

An ab initio study using the local spin density approximation of the electronic and optical properties of materials where Cr transition metal substitutes for N in the GaN host semiconductor with an atomic concentration of 1.56% is presented. This material, characterized by an isolated and partially filled intermediate band, is a candidate for high-efficiency solar cells. The atomic and orbital composition of this band has been analyzed showing that is mainly made up of a t-group orbital of the transition metal. The absorption coefficient theoretical results show a sub-gap absorption with respect to the host semiconductor which could lead to an increase in solar conversion efficiency.     

FODA — the formal specification of ODA document structures and its use as a basis for conformance testing

The Office Document Architecture (ODA) is an International Standard which is developed by TC 97/sc 18 of the International Organization for Standardization (ISO) in close collaboration with CCITT's Study Group VIII and with ECMA. This paper describes the current state of a formal specification of the ODA document structures by mathematical means and its use for conformance specification and conformance testing.     

电子仪器发展趋势

本文在回顾了电子仪器近百年发展的历史的基础上,对国际电子仪器制造商、电子仪器行业及电子仪器本身的发展趋势,以及我国电子仪器的发展情况进行了分析归纳和总结.     

First-principle study of ferroelectricity in PbTiO3/SrTiO3 superlattices

We performed the first-principles calculation to investigate the electronic structure and polarization behaviors in PbTiO₃/SrTiO₃ (PST) superlattices. The DOS (density of state) profiles show that there are strong hybridizations of atom Ti–O and Pb–O which play very important roles on ferroelectricity of the PbTiO₃/SrTiO₃ superlattices. Comparing to the corresponding paraelectric phase, we find the electrons of the PT (PbTiO₃) layers occupy lower energy states and electrons of the ST (SrTiO₃) layer occupy higher energy states. It is shown that the polarizations of the superlattices decrease with proportion of SrTiO₃ increasing. The constant polarization of local layer indicates that PST superlattices with small modulation lengthen can be approximately considered as a single ferroelectric material. Furthermore, according to electrostatic model, we find that directions of internal electric fields in PT and ST layers are opposite. In PST superlattices, internal electric field in PT layer leads to the loss of polarization of this layer, but the polarization of ST layer is induced by internal electric field of this layer. Compared to the value of the polarization in bulk PbTiO₃, polarization of PST is smaller.     

Electronic protection and routing optimization of MANETs operating in an electronic warfare environment

Domination of the electromagnetic spectrum is a crucial component of the 21st century warfare. In the harsh electromagnetic environment of the modern battlefield, it is of the utmost importance to deny the opposing force the opportunity to attack or exploit the detection/interception of friendly communications assets through the deployment of electronic protection (EP) measures in order to attain low probability of detection (LPD), low probability of interception (LPI) and anti-jam (A/J). Given that directional antennas are a suitable means to achieve both extended range and LPD/LPI, this paper proposes mechanisms to optimize the trade-off between these capabilities, minimizing the number of hops and end-to-end delay when routing packets in a multi-hop ad-hoc network, while taking into account stealth requirements. The novel scheme is based on a variant of Fisheye State Routing, coupled with a power control algorithm to guarantee a LPD/LPI beyond the zone covered by the omni-directional radiation footprint of the network. The performance of the proposed scheme is evaluated through computer simulation.     

The medium matters: Mining the long-promised merit of group interaction in creative idea generation tasks in a meta-analysis of the electronic group brainstorming literature

This meta-analysis examines the influence of electronic communication media on group idea generation tasks. Data from the following three areas of the brainstorming literature are synthesized to assess differences across performance variables and group member satisfaction: (1) electronic brainstorming (EBS) groups versus traditional face-to-face (FTF) interacting groups, (2) EBS groups versus nominal groups, and (3) EBS versus electronic nominal (e-nominal) groups. The results of this integration show that EBS groups are more productive and more satisfied with the interaction process than FTF groups. Additionally, large EBS groups outperformed nominal groups, whereas small nominal groups outperformed EBS groups. These findings have important implications for electronic collaboration and teamwork in both academic and organizational settings, especially given the recent proliferation of virtual teamwork.     

Dissociative adsorption of small molecules at vacancies on the graphite (0 0 0 1) surface

The adsorption of molecular and atomic hydrogen as well as other molecules in the atmosphere on vacancies in the (0 0 0 1) graphite surface are investigated using density functional theory. Atomic hydrogen adsorbs with energies ranging from 4.7 to 2.3 eV. The validity of the model is confirmed by the good agreement between calculated vibrational spectra and those of high-resolution electron energy loss spectroscopy. It is shown that molecular hydrogen dissociates with a barrier of 1.1 eV on this model system. Water and oxygen also dissociate with respective barriers of 1.6 and 0.2 eV. Carbon dioxide and nitrogen have no interaction with the defect whereas carbon monoxide is incorporated into the vacancy with an activation energy of 1.5 eV. A comparison is made with the reactivity of graphene edges, both zigzag and armchair.     

由IR2155驱动的高功率因数电子镇流器

本文介绍了一种由ＩＲ２１５５驱动的电子镇流器功能特点和工作原理。