Penumbral imaging and numerical evaluation of large area source neutron imaging system

The fusion neutron penumbral imaging system Monte Carlo model was established. The transfer functions of the two discrete units in the neutron source were obtained in two situations: Imaging in geometrical near-optical and real situation. The spatial resolutions of the imaging system in two situations were evaluated and compared. The penumbral images of four units in the source were obtained by means of 2-dimensional (2D) convolution and Monte Carlo simulation. The penumbral images were reconstructed with the same method of filter. The same results were confirmed. The encoding essence of penumbral imaging was revealed. With MCNP(Monte Carlo N-particle) simulation, the neutron penumbral images of the large area source (200 μm×200 μm) on scintillation fiber array were obtained. The improved Wiener filter method was used to reconstruct the penumbral image and the source image was obtained. The results agree with the preset neutron source image. The feasibility of the neutron imaging system was verified. Supported by the NSAF Joint Fund set up by NSFC and CAEP (Grant No. 10576022)     

Requirement of ultra-high voltage GIS arrester to voltage gradient of metal-oxide varistor

The surge arrester with excellent protection characteristics would decrease the overvoltage level ap- plied on the power apparatus to reduce their insulation levels and manufacturing bottleneck. The arrester for the 1000-kV ultra-high voltage ac power transmission system is designed as tank-type structure. The field-circuit combination numerical method combining the three-dimensional finite element method with circuit is proposed to analyze the potential distribution of GIS arrester. By comparing several design schemes, the most effective method to improve the potential distribution along the varistor column is to increase the voltage gradient of the ZnO varistor. Synthesizing several influential factors, the suitable voltage gradient of ZnO varistor should be controlled to 435 V/mm, and the resulted nonuniform degree of the potential distribution along the varistor column inside the GIS arrester would be controlled smaller than 10%. The result in this paper provides the fundamental technical index for the study of the high voltage gradient ZnO varistors.     

Multi-channel micro neural probe fabricated with SOI

Silicon-on-insulator(SOI) substrate is widely used in micro-electro-mechanical systems(MEMS).With the buried oxide layer of SOI acting as an etching stop,silicon based micro neural probe can be fabri-cated with improved uniformity and manufacturability.A seven-record-site neural probe was formed by inductive-coupled plasma(ICP) dry etching of an SOI substrate.The thickness of the probe is 15 μm.The shaft of the probe has dimensions of 3 mm×100 μm×15 μm with typical area of the record site of 78.5 μm2.The im...     

Growth of Ag nanocrystals on multiwalled carbon nanotubes and Ag-carbon nanotube interaction

The experimental investigations on the interaction between Ag-nanocrystal particles (Ag-NCPs) and carbon nanotubes (CNTs) in Ag-nanocrystal particles/carbon nanotubes (Ag-NCPs/CNTs) hybrid structures were reported. The growth of Ag-NCPs on multiwalled carbon nanotubes (MWCNTs) was carried out by thermal evaporation deposition. High-resolution transmission electron microscopy and X-ray diffraction analyses revealed that Ag-NCPs had the crystal lattice feature of face-centered cube (fcc). The growth of Ag-NCPs on MWCNTs induced the cross-section deformation of MWCNT. The experimental results also showed that the synthesized Ag-NCPs/CNTs hybrid structure appeared as quasi-one dimensional nanowires containing the Ag-NCP/CNT hetero-junction. There was local cross-section deformation on MWCNTs at the interface of hetero-junction. These results involve the important topic about fundamental and practical studies for structure of MNCPs on CNTs and also find clues to further research of Ag nanocrystal growing on MWCNTs and related Ag-CNT interaction.     

Composite silicone rubber of high piezoresistance repeatability filled with nanoparticles

The ruthenium oxide nanoparticles with size less than 20 nm were fabricated by annealing the metallic ruthenium nanoparticles in air, which were synthesized by using the thermal reduction in the polyol solution. The rutile structure of the ruthenium oxide was proved by using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The oxide has good electron conductivity. The surface of the ruthenium oxide was modified by a vinyl silane coupling agent. The assembling of the silane to the oxide surface was proved by Infrared (IR) absorption spectroscopy. By mixing the nanoparticles with poly(methylvinylsiloxane) (PMVS) silicone rubber, a composite filled with dispersive conducting phase was fabricated. The temperature dependent conductivity shows that the electron transportation through composite is mainly dominated by tunneling. The measurement of piezoresistance shows that the composite at low strain has high piezoresistance repeatability. The 3D reconstruction images of the composite filled with carbon black or ruthenium oxide show that the aggregation of the nanoparticles differs much for two composites. The narrow distribution range of the particle size was thought to be the main factor for the high piezoresistance recurrence.     

采用磁选和重选回收废旧电路板中的金属

采用磁选和重选联合工艺回收废旧印刷电路板中Fe、Cu、Al、Pb、Zn、Sn和Ni等金属。结果表明,采用干法磁选工艺,可回收的铁磁性物质约占废旧电路板质量分数的8．23％,重液分选可使金属与非金属有效分离,采用磁选和重选联合工艺可使Fe、Cu、Pb、Zn、Ni和Sn的回收率分别达到约100％、80％、65％、75％、88％和56％。     

压电陶瓷在声速测量中的应用

本文论述了压电陶瓷在声速测量中的应用,阐述了几种测量超声波波速的方法。     

HDLC协议一致性测试系统的研究

HDLC协议一致性测试是保证不同厂家生产的HDLC通信设备之间实现互联、互通和互操作的前提;在对协议一致性测试基本工作原理进行简要分析的基础上,提出了HDLC协议一致性测试的基本方法以及测试过程中基于FSM模型的数据收发处理机制;并在实验室环境下构建了一致性测试硬件平台,设计了测试准备、测试执行和测试评估相关环节所涉及的基本软件功能模块,完成了HDLC协议一致性测试的基本功能;实际运行和测试结果表明,所设计的测试系统达到了预期结果;目前,该系统已成功应用于高速动车组上的通信测试,测试案例可以根据实际需求进行添加、删除和修改,提高了一致性测试的灵活性和完备性。     

建筑卫生陶瓷行业竞争环境SWOT分析

文章通过大量的调查研究,概述了中国特别是广东省建筑卫生陶瓷企业的现状,采用SWOT分析方法,对该行业的企业所处的优势、劣势、面对的机遇和挑战进行了全面的研究分析,预测了建筑卫生陶瓷未来发展的总体趋势。     

加强产学研用深度合作,突出工程硕士工程实践能力培养

工程硕士专业学位教育强调工程性、实践性和应用性,旨在培养适应经济社会发展的应用型、复合型高层次工程技术和工程管理人才。兰州理工大学从培养方案修订、课程改革、实践基地建设、质量保障体系建立等方面对全日制工程硕士研究生的培养模式进行改革,加强产学研用深度合作,突出工程实践能力培养,取得了一定成效。