超磁致伸缩致动器的磁-机械强耦合模型

稀土一铁超磁致伸缩材料作为一种新型功能材料，其应用越来越受到人们的关注。为了有效地设计、开发超磁致伸缩材料的器件，必须建立材料器件的输入输出模型。利用能量变分原理，针对研制的超磁致伸缩致动器，建立了系统的磁一机械强耦合模型，并应用有限元法计算了致动器的输入电流与输出位移的关系曲线。计算值与实验值比较吻合，表明所建立的模型能够反映致动器的输入输出关系，模型对于设计超磁致伸缩器件、优化设计方案具有重要意义。     

制罐机用大功率晶体管(GTR)电阻焊的逆变电源

本文介绍了一种以ＴＰ８０１Ａ微机为控制核心的大功率晶体管逆变式电阻焊电源，主电路采用ＧＴＲ桥式逆变电路，在焊机次级回路中，获得频率为１２０－２６０Ｈｚ的焊接电流，以适应罐头高速缝焊的需要。     

超磁致伸缩材料的工程应用研究现状

系统地介绍了国内外稀土超磁致伸缩材料在各工程领域中的应用及其开发概况,剖析了基于该材料的各种应用器件的原理与结构,并对其性能作了阐述。重点介绍了稀土铁系超磁致伸缩材料在机电工程中的应用,并对该材料未来的发展及应用领域作了展望。     

中国寻找大油气田的主要方向与目标区选择

我国中、西部地域辽阔,石油地质条件优越,是发展我国石油工业的后备基地。优选出了10个勘探目标区作为“九五”期间我国中、西部地区油气勘探的重点区带。为了适应这一新形势,应把全国区域地质研究的重点放在西部地区,并开展物探、钻井、测井、测试、录井等方面的技术、工艺攻关课题研究。     

超磁致伸缩驱动器动态输出特性的改进研究

针对超磁致伸缩驱动器的动态输出特性的响应问题,从驱动器的驱动电源和控制算法两方面人手,提出了改进方法,并形成了一个完整的计算机测控系统。试验表明,该系统简单、可靠、实用,所提出的控制算法和驱动电源对超磁致伸缩驱动器的动态输出特性有明显的改进。     

Giant piezoelectricity,rhombohedral-orthorhombic-tetragonal phase coexistence and domain configurations of (K,Na)(Nb,Sb)O3–BiFeO3–(Bi,Na)ZrO3 ceramics

Research on lead-free piezoelectric ceramics has been an important subject in recent years due to increasingly strong environmental concerns. In this paper, we report the piezoelectric performance, phase transitions and domain structure for a series of dense (0.994-x)(K_0.40Na_0.60)(Nb_0.955Sb_0.045)O₃–0.006BiFeO₃–x(Bi_0.50Na_0.50)ZrO₃ ceramics prepared by two step-sintering through solid-state reaction. Among these ceramics, the one with x = 0.03 shows a giant piezoelectricity with remarkably high piezoelectric coefficient d₃₃ of 550 pC/N at room temperature. Concurrent measurements of ε′ and ε′′ vs. temperature dependences and X-ray diffraction analysis showed that ceramics with x ≤ 0.04 are in rhombohedral-orthorhombic-tetragonal (R-O-T) phase coexistence at room temperature. More intriguingly, the rhombohedral-orthorhombic phase transition temperature, T_R-O, is almost independent of the (Bi_0.50Na_0.50)ZrO₃ content, while orthorhombic-tetragonal phase transition temperature, T _O-T, decreases largely with increasing the (Bi_0.50Na_0.50)ZrO₃ content. Domain configurations of the ceramic with x = 0.03 were investigated by acid-etching. Complicated domain patterns consisting of watermark-shaped domains of long parallel stripes separated by irregularly shaped boundaries are seen before poling. In contrast, relatively simple domain patterns of long parallel stripes with some nanodomains appearing in a part of broad stripes are observed after poling. The obtained excellent piezoelectric properties are ascribed to the R-O-T phase coexistence and the corresponding characteristic domain structure.     

Electrodeposition of Co-Ni-Cu/Cu multilayers: 1. Composition, structure and magnetotransport properties

Co-Ni-Cu/Cu multilayers have been deposited from a sulfate/sulfamate bath by controlling the current and the potential for the deposition of the magnetic and the copper layer, respectively. The magnetic layer thickness was varied between 1.2 nm and 12 nm, while the Cu layer thickness was in the range of 1.1-2.3 nm. Alloys with direct current have also been produced for comparison. All multilayer deposits exhibited a face centered cubic structure, while a small amount of hexagonal close packed phase was also present in the d.c. deposited alloys. The composition analysis showed that the codeposition of Co and Ni can be classified as anomalous codeposition for both d.c. and compositionally modulated deposits, regardless of the simultaneous deposition of Cu. The composition of the magnetic layer was affected by its layer thickness. This finding led to the conclusion that there must be a composition gradient in the magnetic layer in the growth direction. The magnetoresistance of the multilayers increased with increasing copper layer thickness, while the superparamagnetic contribution in the magnetoresistance increased with decreasing deposition current density of the magnetic layers.     

巨应力阻抗效应测量系统的设计研究

根据巨应力阻抗效应的检测原理以及巨应力阻抗材料应变因子的定义,对其检测系统的结构和工作原理进行了设计研究.重点设计了张力加载装置,并提出了消除测量样品安装误差的解决方案.     

Characterisation of CoNi(Cu)/Cu multilayers deposited from a citrate electrolyte in a flow channel cell

CoNi(Cu)/Cu multilayers consisting of 50 and 200 bi-layers were deposited from a citrate electrolyte in a flow channel cell by a dual pulse plating technique. The dissolution of the ferromagnetic components during pulse plating was studied using an oscilloscope and cyclic voltammetry. It was found that the dissolution was suppressed due to the passivation of the ferromagnetic layers before the deposition of an atomic layer of nonmagnetic component on them. The passivation was a function of the nickel ion concentration in the electrolyte. X-ray studies showed that the deposit had a preferred crystal orientation of [1 1 1] and suggested the formation of a super-lattice. Atomic force microscopy studies showed a four-fold increase of the roughness of the ferromagnetic surface with increasing layer thickness from 6 to 10 nm, whereas the roughness of the nonmagnetic surface only changed slightly with increasing layer thickness. The multilayers exhibit giant magnetoresistance.     

非线性Preisach理论与超磁致伸缩执行器高阶迟滞建模

经典Preisach理论在建模迟滞过程时要求其所描述迟滞过程必须满足擦除特性和滞环全等特性,并把这两个条件作为其建模的充分与必要条件。试验表明超磁致伸缩材料的迟滞过程仅满足擦除特性而不满足滞环全等要求,正是这个原因使经典模型在预测具有多次回转特征的高阶迟滞输出时存在较大误差。在经典模型基础上提出一种改进模型,新模型一方面放松经典模型对次环全等的严格要求,另一方面还在参数辨识过程中同时将一阶和二阶回转曲线数据考虑在内,从而提高其对高阶回转迟滞曲线的预测精度。最后在直动式超磁致伸缩执行器上进行试验。结果表明,在预测具有多次回转特征的高阶迟滞输出时,新模型的预测精度明显高于经典模型,对二阶、三阶滞回曲线的预测精度分别提高了34%和33%。