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。     

GMM微泵柔性铰链输出薄膜的结构设计与优化

由于超磁致伸缩高频微泵的普通输出杆与泵腔内壁频繁摩擦产生的损耗,影响泵腔的密封性,从而导致油液泄漏。为解决这一问题,提出一种复合型柔性铰链薄膜取代普通输出杆,并对各种柔性铰链薄膜进行有限元建模及分析,由仿真结果和理论分析得出:该复合型柔性铰链薄膜转动能力强,回转精度高,结构尺寸小,运动灵敏度高,从而减小柔性铰链薄膜与泵腔内壁的摩擦,为以后GMM微泵的设计提供理论基础。     

超磁致伸缩驱动器磁场输出位移的有限元分析

在建立超磁致伸缩微驱动器的轴对称模型的基础上，利用有限元方法对驱动器的磁场进行分析，并通过数值积分方法计算在不同励磁电流下超磁致伸缩棒的伸长量，根据计算结果对驱动器的线性工作范围作出了有效的估计。     

超磁致伸缩驱动器磁致伸缩模型的有限元分析

超磁致伸缩驱动器具有响应速度快、输出力大、磁机耦合系数高等诸多优点,但因其磁致伸缩模型具有磁滞非线性特性,在设计超磁致伸缩驱动器过程中,主要是建立准确描述其磁滞非线性的数学模型。为有效提高超磁致伸缩驱动器的设计效率,以磁致伸缩产生机制为基础,将Jiles-Atherton磁滞模型和压磁方程结合,建立超磁致伸缩驱动器的非线性本构模型,并推导超磁致伸缩驱动器机械应力场弱解形式的控制方程。最后,基于有限元方法在COMSOL Multiphysics多物理场耦合软件平台中实现其磁致伸缩模型的仿真,得出了一种高效率的超磁致伸缩驱动器的设计方法。     

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.     

Enhanced permittivity and permeability of (1-y)(Mg0.95Zn0.05)2TiO4-yMg0.95Zn0.05Fe2O4 ceramics

We report the preparation of the solid-solutions (1-y)(Mg_0.95Zn_0.05)₂TiO₄-yMg_0.95Zn_0.05Fe₂O₄ (y = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) by traditional solid-state reaction and systematically study their phases, morphologies, and magnetodielectric properties. The giant dielectric constants are observed at low frequency in the ceramics, with y > 0.5 when the sintering temperature exceeds 1200 $℃$. The highest relative permittivity ${\epsilon }^{\text{'}}$ of 9.98?×?10³ at 30?kHz and the largest squareness ratio of 0.89 for the magnetic hysteresis loop are achieved in 0.1MZT-0.9MZF. In addition, the enhanced initial permeability ${\mu }_i$ of ～70 is obtained in 0.3MZT-0.7MZF due to its large grain size and probably the smaller magnetostriction and internal stress caused by lower relative density. All the results indicate that our solid-solutions with y > 0.5 can considerably improve the dielectric and magnetic properties, providing more advantages than the simple bi-phasic compounds in the applications for novel electronic devices.     

特种炭黑BL104与炭黑N115在全钢巨型工程机械子午线轮胎胎面胶中的应用对比研究

对比研究特种炭黑BL104与N115炭黑在全钢巨型工程机械子午线轮胎胎面胶中的应用。结果表明：与炭黑N115硫化胶相比,特种炭黑BL104硫化胶的磨耗性能、耐热老化性能提高,降低硫化胶生热性能。     

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.     

Giant magnetostriction in magnetite nanoparticles

Typically the value of the magnetostrictive coefficient (λ) observed for bulk magnetic materials such as cubic ferrites is 10⁻⁶. However, giant magnetostriction (λ ≤ 10⁻³) is only observed in a few bulk intermetallic materials based on alloys of rare earth and iron such as TbFe, TbFe₂, DyFe₂ and Terefenol-D. While giant magnetostriction is known in nanostructured films, we show for the first time, this phenomenon occurs in magnetic nanoparticles. By using in-field small angle X-ray scattering (SAXS) as a tool, we demonstrate that a 4% relative change in dimension of the particle can be observed in 5.0 nm Fe₃O₄ nanoparticles at room temperature with 1 kG magnetic field. Also, we propose that the observed values are due to interaction effects and magnetoelastic coupling of particle magnetic moments and external magnetic field.     

Giant Mine: Identification of Inflow Water Types and Preliminary Geochemical Monitoring during Reflooding

Abstract:  Between 1948 and 1999, gold ore containing high concentrations of arsenopyrite was mined at the Giant Mine near Yellowknife, Canada. Processing resulted in 215,000 kg of gold and approximately 237,000 tonnes of highly soluble arsenic trioxide, a by-product of the roasting process. The arsenic dust was collected and placed underground in 15 shallow chambers and stopes (within 75m of the surface) with the understanding that the ground would revert to permafrost conditions once mining was completed. Subsequent studies have shown that the ground is unlikely to refreeze naturally; therefore, it has been proposed to actively freeze the arsenic trioxide storage areas to hydraulically isolate them from the post-closure ground water system. However, other arsenic sources (backfilled tailings, etc.) exist deeper in the mine (600 m total depth), so there is a concern that arsenic will leach into the minewater system and ultimately into the environment when the mine is allowed to flood. Therefore, the development and implementation of a remediation plan for the site requires a good understanding of the arsenic distribution and expected release to the mine water. To gain this understanding, a detailed program of surface and underground sampling was carried out to identify or “type” the inflow sources to the mine, and their interaction with arsenic sources both on the surface and within the mine workings. As of July 2005, the mine has been allowed to begin reflooding to reduce pumping costs and remove the need for servicing pumps at the bottom of the mine, thus allowing the main shaft to be taken out of service. Prior to starting reflooding, a multi-level monitoring system was installed in the main shaft and is currently being used to monitor reflooding levels and water chemistry. Samples can be collected from each mine level intersecting the shaft. The system will monitor reflooding rate and test how underground arsenic sources (backfilled tailings, etc.) are affecting water quality in the mine. This geochemical information will be used to assess long-term arsenic loading from sources outside the frozen zone and predict how long mine water treatment will be needed before natural ground water flow can be allowed.