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.     

RH真空处理GCr15轴承钢中全氧及显微夹杂物的行为研究

针对RH工艺生产轴承钢,通过现场试验研究了RH真空处理时间对钢中全氧和显微夹杂物的影响.试验结果表明,延长RH真空时间可以进一步降低钢中全氧和显微夹杂物的数量,RH脱氧主要是通过显微夹杂物的去除,全氧与显微夹杂物随时间的变化关系基本一致;真空处理25min可使钢液中全氧和显微夹杂降低约60%,比14min时多降低约13%,并得出邢钢轴承钢生产条件下,RH精炼过程钢液的表观脱氧速度系数为-0.036min-1;工艺优化后147炉轴承钢产品的平均全氧为6.7×10-6.     

Isolation and Properties of Melanin in Fine Yak Hair

Melanin granules were isolated from fine yak hair by means of protein enzyme and hydrochloric acid.Resultsof SEM investigation and amino acid analysis were usedto study the physical and chemical properties of melaningranules.The solubility of melanin granules in differentchemical solutions was also studied.     

Global view of Hopf bifurcations of a van der Pol oscillator with delayed state feedback

This paper presents both analytical and numerical studies on the global view of Hopf bifurcations of a van der Pol oscillator with delayed state feedback. Based on a detailed analysis of the stability switches of the trivial equilibrium of the system, the stability charts are given in a parameter space consisting of the time delay and the feedback gains. The center manifold reduction and the normal form method are used to study Hopf bifurcations with respect to the time delay. To gain an insight into the pe...     

新疆维、哈、蒙、汉大学生体质健康测试的比较分析

以不同民族一年级大学生身高体重的五个等级为变量,分别与各体质健康测试项目等级所占的百分率之间的进行比较分析,发现维吾尔族和哈萨克族男生的速度灵敏类项目表现优异,蒙古族男女生的柔韧类项目表现优异,汉族女生的耐力类项目表现超过汉族男生,而他们的体质健康标准测试总分合格率只有60.6%,说明大学生身体素质的发展不够全面,在不同民族男女大学生之间存在差异性,总体滑坡依然存在。     

Structure Characterization of Silk Fibroin Crystalline Domain Polypeptides Expressed in Escherichia coli

The molecular conformations of four silk fibroin crystalline analogues [GAGAG-X] 16(G,Gly;A,Ala;X=Ala,Ser,Tyr or Val,designated eGA,eGS,eGY or eGV),carried out using molecular design and expressed by Escherichia coil(E.coli),were evaluated by Raman spectra analysis.The abilities of forming β-sheet structure were determined by thioflavin T(ThT) fluorescence spectra analysis.In terms of molecular conformation,except eGY that could not form significant typical molecular conformation,eGS and eGV were mainly com...     

In-plane elastic stability of fixed parabolic shallow arches

The nonlinear behavior of fixed parabolic shallow arches subjected to a vertical uniform load is investigated to evaluate the in-plane buckling load.The virtual work principle method is used to establish the non-linear equilibrium and buckling equations.Analytical solutions for the non-linear in-plane symmetric snap-through and antisymmetric bifurcation buckling loads are obtained.Based on the least square method,an approximation for the symmetric buckling load of fixed parabolic arch is proposed to simplif...     

Influence of Spinning Technology on Dye Uptake of Modified Polypropylene Fiber

By adding small amount of olefin polymer additive, the dyeability of polypropylene fiber can be improved. Research results show that the improvement of dyeing performance of modified PP fiber is mainly due to the formation of looser structure of PP matrix and the micro-channels among additive particles in blended fiber. The dye uptake of drawn fibers decreases with drawing ratios obviously and changes with temperature of heat plate and heat roller a little.     

Wet Permeability and Moisture Vapor Transmission Characteristics of Soybean Knitted Fabrics

Wet permeability of fibrous assembly is mainly influenced by the properties of liquid and the configurations of the fiber which consist of diameter of fiber, twist angle and fiber alignment in a yarn. It can be seen from experimental results that the knitted fabric made of soybean (SB) fiber has good properties both in wet permeability and vapor transmission so that the knitting technology and fabric characteristics can be improved.     

电子阅览室内部设计与布线

就长春大学图书馆电子阅览室的声、光、色、温及家俱等环境设计与实现 ,以及环境与读者使用电子阅览室的关系等问题 ,作了较为详尽的探讨 ;对网络布线的设计与运作 ,以及在布线建设和施工当中需要注意的问题作了必要的说明