层合板状纺织结构梯度复合材料的研制

本文介绍了层合板状结构，针对其受弯曲负荷时进行了非均匀化设计，同时利用多层纺织技术设计和织造了梯度结构的机织物，研制成功了层合板纺织结构梯度复合材料，并和一般单层叠加而成复合材料进行了比较。     

聚烯烃高效载体催化剂的研究

本文以MgCl2、SiO2为载体,研制了多种配方的Ziegler-Natta钛系高效最体催化剂.在实验过程中改变MgCl2、SiO2、甲基硅油等加入量,改变反应时间、反应温度,并对催化剂组成进行了化学分析.在分析敷据的基础上进行乙烯及丙烯的聚合实验,对产品进行性能分析,确定原料加入量、反应时间、反应温度等对催化剂效率、产品性能的影响.     

Electrochemical behaviour of Ni-cermet anodes containing a proton-conducting ceramic phase on YSZ substrate

Solid oxide fuel cell cermet anodes with proton-conducting ceramic phases, Ni-SrZr_0.95Y_0.05O_2.975 (Ni-SZY), Ni-CaZr_0.95Y_0.05O_2.975 (Ni-CZY) and Ni-SrCe_0.475Zr_0.475Y_0.05O_2.975 (Ni-SCZY), have been analysed by electrochemical impedance spectroscopy. The anodes were sintered on opposing faces of yttria-stabilised zirconia (YSZ) electrolyte and the polarisation behaviour studied in the temperature range 600-900 °C in various regimes of H₂ and H₂O partial pressures. The ceramic component of the Ni-CZY and Ni-SCZY cermets form an insulating phase at the interface with YSZ. Impedance spectra are composed of two dominant rate-limiting contributions attributable to electrode processes with relaxation frequencies ca. 10³ and 1 Hz at 800 °C. Both high- and low-frequency responses are sensitive to H₂O partial pressure and temperature, with activation energies in the range 1.02-1.25 and 1.19-1.35 eV, respectively. Factors influencing the origin of the rate-limiting processes are discussed, including transport limitations (oxide-ion and electronic) in the solid phases and microstructure. Proton conductivity may assist in accelerating the kinetics of the anodic reaction by widening the effective reaction area in electrodes optimised in terms of Ni content, oxide-ion conductivity and microstructure.     

Quaternary Ammonium Salts (QAS) Modified Polysiloxane Biocide Supported on Silica Materials

Three types of silica particles modified with vinyl groups were obtained: (i) xerogel formed by hydrolytic polycondensation of the mixture of tetramethoxysilane (TMOS) and 1,1,1,7−tetramethoxy-3,5,7-trimethyl-3,5,7-trivinyltetrasiloxane, (ii) mesoporous silica obtained from the same precursors in the presence of the cetyltrimethylammonium bromide (CTAB), and (iii) commercial Fluka silica gel 60A with a vinyltriethoxysilane-treated surface. Vinyl groups on these silica materials were transformed into silyl chloride by hydrosilylation with HMe₂SiCl. These groups were used to graft living polysiloxane that was synthesized by anionic ring-opening polymerization of 2,4,6-tri(3-chloropropyl)-2,4,6-trimethylcyclotrisiloxane and initiated by BuLi. Chloropropyl groups on the grafted polymer were used to quaternize N,N-dimethyl-n-octylamine. Silica particles with grafted polysiloxane having quaternary ammonium salt (QAS) groups pendant to polymer chains were obtained. Silica material with QAS groups directly attached to the surface were generated by the action of N,N-dimethyl-n-octylamine on particles obtained by the sol–gel process involving tetraethoxysilane (TEOS) with 3-chloropropyltriethoxysilane. The bacteriocidal properties of all these materials were tested in water suspension against five representative strains for Gram-positive and Gram-negative bacteria. Some of the silica–polysiloxane hybrid materials have good antibacterial properties against Gram-positive strains, but not as good as the non-tethered QAS-substituted polysiloxane in water solution. The QAS groups that are directly bonded to the silica material surface are inactive.     

Corrosion of amorphous and nanocrystalline Fe-based alloys and its influence on their magnetic behavior

Nanocrystalline soft magnetic materials with low coercivity, high saturation magnetization and high permeability are commonly used as cores in transformers and generators in stress and field sensors. The influence of factors connected with corrosion is almost impossible to eliminate. In the present work, a comparative study of the electrochemical behavior of Fe₇₈Si₁₃B₉ and Fe_73.5Si_13.5B₉Nb₃Cu₁ amorphous and nanocrystallized alloys, tested in 0.5 M NaCl solution, has been performed by linear polarization and electrochemical impedance spectroscopy methods. Changes of magnetic properties including coercivity, induction and magnetic retentivity were analyzed. These properties were investigated as a function of the structure of primary amorphous ribbons and as a function of corrosion environment type, in which longitudinally and transversely cut ribbon specimens were exposed for 15 days. The best magnetic properties were found for the Fe₇₈Si₉B₁₃ ribbon after a structural relaxation at a temperature of 350 °C for an hour and for the Fe_73.5Si_13.5B₉Nb₃Cu₁ ribbon after a primary crystallization at a temperature of 550 °C for an hour. Corrosion did not cause the direct degradation of the magnetic properties of the Fe₇₈Si₉B₁₃ and Fe_73.5Si_13.5B₉Nb₃Cu₁ alloys. The corrosion processes occurring on the surface of the Fe_73.5Si_13.5B₉Nb₃Cu₁ alloy ribbon with the amorphous structures improve induction B_s. Most probably it is connected with the decrease of undesirable stresses blocking a motion of magnetic domain walls on the ribbon surface. Changes of corrosion mechanism depending on structure and applied solution were analyzed. The electrochemical impedance experiment were performed at open circuit potential for amorphous and nanocrystalline specimens. Two electrochemical corrosion mechanisms of Fe_73.5Si_13.5B₉Nb₃Cu₁ alloy in 0.5 M NaCl solution were found. Charge transfer control mechanism is typical for amorphous (as received) alloys. Mixed mechanism-mass transport and charge transfer controlled was observed for nanocrystalline Fe_73.5Si_13.5B₉Nb₃Cu₁ alloy.     

基于热传导原理的企业风险传导研究

企业风险具有传导性。基于热传导原理，界定了企业风险传导涵义，包括企业内部风险传导和企业间风险传导。剖析了企业风险传导的条件，认为风险传导必须借助特定载体并依赖一定路径。同时探讨了企业风险传导重点研究的问题，主要有风险识别、风险估量，以及风险传导载体的辨识和路径的判断。     

电力线载波通信技术在楼宇智能监控中的应用

介绍了一种基于电力线载波的楼宇智能控制系统的实现方法。其以LM567为核心，通过调制发送和解调接收，在电力线上实现了语音信号和控制信号的复用传输。     

用厚度阈值法改善深拉延冲压件坯料形状预测精度

将作者首次提出的厚度阈值法应用到基于逆有限元原理的坯料形状预测算法中,有效地改进了深拉延冲压件坯料形状预测的精度,并以某汽车油底壳拉延件为实际算例,分别用改进前和改进后的算法,对其坯料形状进行预测,预测结果与实际坯料形状的对比结果验证了本文方法的有效性。     

双Logistic映射下隐藏数字图像的新方法

在Logistic映射基础上,设计了一种隐藏数字图像的新方法.该方案采用两组参数不同的混沌映射生成双混沌序列,利用非线性规则从每个混沌序列中构造出两组实值序列,分别用于置乱和加密数字图像阵列,从而得到失去原图像任何特征的秘密图像,最后将秘密图像嵌入隐蔽载体中完成隐藏数字图像的过程.该方案增强了隐蔽载体的鲁棒性,提高了抗恶意攻击的能力.     

Mode III fracture of a magnetoelectroelastic layer: exact solution and discussion of the crack face electromagnetic boundary conditions

This paper develops a closed-form solution for anti-plane mechanical and in plane electric and magnetic fields in a magnetoelectroelastic layer of finite thickness. Explicit expressions for the stresses, electric fields, and magnetic fields, together with their intensity factors are obtained for the extreme cases for impermeable and permeable cracks. Solutions for some special cases, such as a magnetoelectroelastic layer with infinite thickness, are also obtained. Applicability of the crack face electromagnetic boundary conditions is discussed. It is found that the crack profile is important in obtaining the correct electromagnetic fields and their intensity factors. The stress intensity factor, however, does not depend on the crack face electromagnetic boundary condition assumptions.