BaTiO3系PTCR材料电学性能的复阻抗解析

采用复阻抗解析法研究了ＢａＴｉＯ３系ＰＴＣＲ材料晶粒、晶界的电学性能。结果表明：使用欧姆接触电极的ＰＴＣＲ材料等效电路的复阻抗为：晶粒电阻呈ＮＴＣ特性，而晶界电阻天Ｔ〈Ｔｃ时呈ＮＴＣ特性，Ｔ〉Ｔｃ时呈明显的ＰＴＣ特性；ＰＴＣ效应是一种晶界效应。     

Adaptive variational models for image decomposition

Image decomposition refers to the splitting of an image into two or more components.In this paper,a clean image is separated into two parts:one is the cartoon component,consisting only of geometric structure,and the other is the oscillatory component,consisting of texture.Three parts for noisy image are considered:cartoon,texture,and noise.To better decompose an image,we propose two new variational models.In our models,two adaptive regularization terms are introduced.The two regularization terms are determined by an adaptive function which can discriminate the cartoon and texture of an image automatically.Experimental results illustrate the efectiveness of the proposed models for image decomposition.     

Lattice-based key exchange on small integer solution problem

In this paper, we propose a new hard problem, called bilateral inhomogeneous small integer solution （Bi-ISIS）, which can be seen as an extension of the small integer solution problem on lattices. The main idea is that, instead of choosing a rectangle matrix, we choose a square matrix with small rank to generate Bi-ISIS problem without affecting the hardness of the underlying SIS problem. Based on this new problem, we present two new hardness problems： computational Bi-ISIS and decisional problems. As a direct application of these problems, we construct a new lattice-based key exchange （KE） protocol, which is analogous to the classic Diffie- Hellman KE protocol. We prove the security of this protocol and show that it provides better security in case of worst-case hardness of lattice problems, relatively efficient implementations, and great simplicity.     

Effects of oxidation and particle shape on critical volume fractions of silver‐coated copper powders in conductive adhesives for microelectronic applications

The effects of oxidation and particle shape on critical volume fractions of silver‐coated copper powders in conductive adhesives are investigated. Silver‐coated copper powders with spherical and flake‐shaped particles were oxidized at temperatures of 30°C, 175°C and 240°C for two hours and dispersed in an epoxy matrix. As silver‐coated copper powders are oxidized at 30°C and 175°C, the critical volume fractions of the conductive adhesives are slightly affected by oxidation and particle shape at these temperatures. As the oxidation temperature approaches 240°C, the critical volume fractions of the conductive adhesives are strongly affected by oxidation temperature and particle shape, owing to the formation of oxides such as Cu₂O on the surface of silver‐coated copper powder—Cu diffuses from the interior to the surface of silver‐coated copper powder and reacts with the oxygen in the air. Silver‐coated copper powder with flake‐shaped particles shows lower critical volume fractions in conductive adhesives than silver‐coated copper powder with spherically shaped particles. Polym. Eng. Sci. 44:2075–2082, 2004. © 2004 Society of Plastics Engineers.     

改性环氧带锈涂料的研究

研究了以改性环氧树脂和聚乙烯醇缩丁醛为基料的钢铁带锈涂料 ,通过对成膜物质、转化剂、渗透剂、颜料等的研究 ,得到了集稳定、转化、渗透为一体的多功能涂料。经过实验测试 ,该涂料的各项性能指标均达到了设计要求 ,并且本工艺方案简单易行、省时高效 ,具有较高的实用价值。     

Interfacial adhesion reaction of polyethylene and starch blends using maleated polyethylene reactive compatibilizer

The interfacial reaction of the polyethylene (PE)/starch blend system containing the reactive compatibilizer maleated polyethylene (m‐PE) was directly characterized by Fourier transform infrared (FTIR) spectroscopy. A significant amount of anhydride groups on m‐PE existed as hydrolyzed forms, resulting in a large amount of carboxyl groups. Using a vacuum‐heating‐cell designed in the laboratory, the carboxyl groups were successfully transformed into the dehydrolyzed state (i.e., anhydride group). This result enabled the direct spectroscopic observation of chemical reaction occurring at the interface. For the PE/starch blend system containing m‐PE, the chemical reaction at the interface was verified by the evolution of ester and carboxyl groups in the FTIR spectra. The effect of the reactive compatibilizer on the interfacial morphology was also examined by scanning electron micrography (SEM). Enhanced interfacial adhesion was clearly observed for the blend system containing reactive compatibilizer. Tensile strengths of blend systems containing m‐PE also increased noticeably compared with the corresponding system without compatibilizer. A similar observation was made for the breaking elongation data. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 767–776, 2002     

The use of wood pulp and radiation‐modified starch in wastewater treatment

Radiation‐induced graft copolymerization of maize starch/acrylic acid has been performed. Also, natural byproduct wood pulp was used after chemical treatment for the removal of metal ions from the investigated wastewater. The surface and structure morphology of the wood pulp and starch/acrylic acid were investigated by scanning electron microscopy and infrared spectroscopy. The physical parameters, such as swelling, gel percentage, and grafting efficiency (%) of starch/acrylic acid copolymer, were studied. The factors affecting the abilities of the prepared materials for removing heavy metal ions and dyes from aqueous solutions were studied. It was found that the maximum metal uptake is in the following sequence: Fe³⁺ > Cr³⁺ > Pb²⁺ > Cd²⁺. The adsorption capacity of such investigated metal ions increases with the increase of pH values. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

借鉴重点国家网络安全建设经验加快完善我国网络安全保障体系

随着新兴信息技术的快速发展和互联网应用的逐步深入,各国对网络空间的重视程度不断加大,而网络安全已经成为制约网络空间健康发展的瓶颈。在此背景下,美国、欧盟等50多个国家和地区已经出台网络安全相关战略,以加强网络安全建设。为此,有必要借鉴国外先进经验,完善我国网络安全保障体系。本文分析了国内外网络安全形势,介绍了美国、欧盟、俄罗斯等重点国家和地区在网络安全建设方面的主要做法,提出来加快我国网络安全保障体系建设的措施建议。     

电子信息产品数据安全隐患探究

随着信息应用水平的提高,以及网络普及程度的加深,电子信息产品也逐渐地走入人们的生活,给人们带来了许多的方便。但是电子信息产品也面临一系列的数据安全隐患,数据和信息一旦泄露,会给国家、机构、个人造成不小的损失。因此,必须对电子信息产品的数据安全隐患进行探究,并且采取强有力的措施来进行预防。笔者根据实际情况,针对电子信息产品数据安全隐患进行了分析,希望能为广大的相关工作者提供一些参考依据。     

Time optimization of ultraviolet–ozone pretreatment for improving wool fabrics properties

Wool fabrics were exposed to ultraviolet (UV)–ozone treatment for different periods. After exposure, the fabrics were analyzed by Fourior transform infrared spectroscopy (FTIR). Also, the crystallinity and amorphousity regions were followed by an X‐ray diffraction technique. The results were correlated by mechanical properties measurements. After a certain period of exposure, the dyeability and printability were improved because these abilities are strongly related to the percentage ratio of crystallinity regions to amorphousity regions in wool fabrics. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1469–1476, 2002