A Study of Melt Flow Analysis of an ABS-Iron Composite in Fused Deposition Modelling Process

Fused deposition modelling (FDM) is a filament based rapid prototyping system which offers the possibility of introducing new composite material for the FDM process as long as the new material can be made in feedstock filament form. Swinburne has been undertaking extensive research in development of new composite materials involving acrylonitrile-butadiene-styrene (ABS) and other materials including metals. In order to predict the behaviour of new ABS based composite materials in the course of FDM process, it is necessary to investigate the flow of the composite material in liquefier head. No such study is available considering the geometry of the liquefier head. This paper presents 2-D and 3-D numerical analysis of melt flow behaviour of a representative ABS-iron composite through the 90-degree bent tube of the liquefier head of the fused deposition modelling process using ANSYS FLOTRAN and CFX finite element packages. Main flow parameters including temperature, velocity, and pressure drop have been investigated. Filaments of the filled ABS have been fabricated and characterized to verify the possibility of prototyping using the new material on the current FDM machine. Results provide promising information in developing the melt flow modelling of metal-plastic composites and in optimising the FDM parameters for better part quality with such composites.     

Effect of Nano-SiC and Nano-Si Doping on Critical Current Density of MgB_2

The discovery of superconductivity in magnesium diboride (MgB2) has opened up a new field in materials science research. It offers a possibility of a new class of high performance superconducting materials for practical applications because of the relatively low cost of fabrication, high critical current densities (Jc) and fields, large coherence length, absence of weak links, higher Tc(TC = 39K) compared with Nb3Sn and Nb-Ti alloys (two or four times that of Nb,,Sn and Nb-Ti alloys). However, the weak flux pinning in the magnetic field remains a major challenge. This paper reports the most interesting results on nanomaterial (SiC and Si) doping in magnesium diboride. The high density of nano-scale defects introduced by doping is responsible for the enhanced pinning. The fabrication method, critical current density, microstructures, flux pinning and cost for magnesium diboride bulks, wires and tapes are also discussed. It is believed that high performance SiC doped MgB2 will have a great potential for m     

CAPP过程中的约束分析

随着并行工程（ＣＥ）概念的提出，对ＣＩＭ中的一些过程，如计算机辅助工艺规程（ＣＡＰＰ），必须作一个重新的认识、分析和改进，以满足ＣＥ提出的诸多要求．从约束的观点出发，对工艺设计过程中的零件需求、毛坯选择、加工过程选择、机床选择、刀具及辅助设备选择、切削参数选择等阶段及整个工艺设计在制造过程中的作用与要求作了分析．从不同的角度对ＣＡＰＰ的各个阶段和环节提出了不同的需求，以期望这些约束分析能有助于ＣＡＰＰ发展，并适应现代制造工程的需要．     

周期扰动非线性耦合器中的混浊态

借助于Ｐｏｉｎｃａｒｅ图作为测量的基准，该文示出了周期扰动非线性耦合器中湿浊态的存在性。基于周期波导中周期模的耦合原理，文中进一步讨论了混浊态在周期扰动非线性耦合器中起始的机理。     

纳米技术与发展中国家

作者将“nano*”与世界银行确定的每个经济类主题词组合检索，结果发现发展中国家普遍在从事
纳米技术研发。进一步研究表明，尽管发展中国家纳米技术的研发能力随着合作和信息利用的加强而提高，
但是这些国家已经偏离了纳米技术的“社会开发”这一通常被认为是最适于发展中国家的研究宗旨。另外，
对卫生保健相关专利的分析证实，各国实力严重不平衡，存在所谓的“纳米鸿沟”现象。在发展中国家中，
中国拥有的专利权所占份额很高，因此“纳米鸿沟”不仅存在于发展中国家和发达国家之间，在发展中国
家也同样存在。发展中国家的研发水平较低，纳米技术有可能走向以往导致全球技术大分裂的技术老路。     

THE EFFECT OF, ABRASION ON LOW STRESS MECHANICAL PROPERTIES OF FABRIC

The low stress mechanical properties of a pure wool and a wool / polyester blend twill fab-rics which were abraded at various abrasion cycles were measured using the KES-F system andthe Instron tensile machine. The surface change of fabrics before and after abrasion was stu-died by means of scanning electron microscope. With the increasing number of cycles, the re-covery behavior of the fabrics studied in tensile, shear and bending deformation decrease, theantibuckling ability lowers, the friction coefficient increases. The geometric roughness de-creases during the first step of abrasion then enhances with further abrasion. The influence ofabrasion on mechanical properties of the pure wool fabric are larger than that of blend fabric.     

澳大利亚科研诚信管理探析

全球范围内的科研诚信管理越来越重要,尤其是随着机构间和国家间的合作越来越频繁.由于研究经费的申请和论文的发表竞争日趋激烈,科研诚信管理的风险也随之加大.科研管理供应链上的所有参与者,包括政府、基金资助机构、研究机构、研究人员以及学生都应该被纳入科研诚信管理体系.该文分别从政府和机构层面对澳大利亚科研诚信管理结构和政策进...     

Zr基大块非晶挤压特性研究

研究了Zr41.2Ti13.8Cu12.5Ni10Be22.5大块非晶在不同挤压速率和挤压温度等工艺条件下的挤压成形性能.结果表明:合金的流变行为对挤压温度和挤压速率有明显的依赖性.在挤压过程中出现了一个平稳流变的过程,其平稳流变所需的载荷(P1)与合金在高温下屈服强度有关.当应变速率为0.005 mm/s时,从355~415℃温度范围内,保持平稳流变所需的力从1.5 kN到0.5 kN,当温度为395℃,应变速率为0.05 mm/s时,保持平稳流变所需的力高达4 kN.在挤压过程中大块非晶呈现超塑性.     

Layered Fe(Ⅲ) doped TiO_2 thin-film electrodes for the photoelectrocatalytic oxidation of glucose and potassium hydrogen phthalate

Four types of TiO 2 thin-film electrodes were fabricated from TiO 2 and Fe(III) doped TiO 2 sols using a layer-by-layer dip-coating technique. Electrodes fabricated were TF (pure TiO 2 surface, Fe(III)-TiO 2 bottom layer), FT (Fe(III)-TiO 2 surface, pure TiO 2 bottom layer), TT (both layers pure TiO 2 ) and FF (both layers Fe(III)-TiO 2 ). The photoelectrochemical behavior of these electrodes was characterized using linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and steady-stat...