国内外挤压铸造技术发展概况

概述了近几年来国内外挤压铸造技术发展。重点评述了在挤压铸造设备、挤压铸造产品以及在合金材料、复合材料、半固态加工以及模具设计等方面的发展情况。     

75Se源γ射线透照工艺性能试验

通过透照试验,比较75Se源γ射线、192Ir源γ射线与X射线的照相特性,以及不同射线源与不同种类胶片和不同厚度增感屏的组合系统的照相灵敏度;测定了75Se源γ射线的透照厚度与灵敏度的关系,提出了75Se射线照相适用的厚度范围。     

The effects of temperature, relative humidity and reducing gases on the ultraviolet response of ZnO based film bulk acoustic-wave resonator

This study investigated the influence of temperature, relative humidity and reducing gases on the ultraviolet (UV) response of ZnO based film bulk acoustic-wave resonator (FBAR). As temperature increased, the UV response of the FBAR degraded. This was attributed to the softening of the ZnO film with increasing temperature. Water molecules can replace adsorbed oxygen on the ZnO surface. At high relative humidity, more oxygen was replaced by water. In this way, the density of the ZnO film increased and less oxygen was left on the surface to be desorbed by UV, both of which contributed to a lower UV response. Reducing gases, such as acetone, can react with the surface adsorbed oxygen and reduce the density of the ZnO film, resulting in UV response degradation.     

Hydrogen sensor based on Pd-functionalized film bulk acoustic resonator

We present an application of the Pd-functionalized film bulk acoustic resonator for hydrogen detection. The resonator consisted of an AlN piezoelectric stack and a Bragg reflector has a working resonance near 2.23 GHz and a high performance. A 50 nm thick Pd film was coated on the top electrode as a specific layer to capture hydrogen. The absorption of hydrogen can trigger changes of elastic properties of the Pd layer, which affects the resonance frequency of the resonator. The experimental results show that the Pd-functionalized film bulk acoustic resonator can yield a rapid, sensitive, reversible and reproducible response to hydrogen in the concentrations from 0.3% to 2%. The advantages of this sensor, including the simple fabrication process, ease of detection method, rapid response and high sensitivity and working at room temperature, make this promising in the early alarm of hydrogen leaking.     

台达机电产品在塑料薄膜生产线上的应用

本文主要介绍了台达机电产品（触摸屏、PLC、变频器、温控器等）在塑料薄膜生产线上的整合应用。该控制系统操作界面友好简单,结合台达HMI、PLC和变频器等工控产品,实现了设备的技术升级与高效节能,体现出台达自动化产品较高的性价比。运行实践证明,台达产品稳定可靠,控制效率高,值得业界同行借鉴和推广。     

A critical appraisal of javelin high speed cinematography results using a computer flight simulation program

Abstract

Errors in javelin release parameters obtained from high-speed film analysis of real throws have been quantified in order to assess the accuracy of studies that assume a rigid body javelin model when measuring human performance characteristics. Human digitizing errors and the inadequate rigid body javelin model represent increments of up to 6 m in range as predicted by a computer flight simulation program. These errors result from difficulties in digitizing blurred javelin coordinates caused by large release speeds and javelin flutter. Errors in release-pitch rate are as high as 27·0%. Digital filtering methods tend to underestimate transiational and angular speeds such that errors in previous literature represent simulated range increments of up to 29 m. This is owing to the filtering methods interpreting high frequency flutter as noise. It is concluded that present methods in javelin film analysis are inadequate for measuring absolute values of release parameters and need to be revised. Accurate quantification is essential before simulation programs can be used in a human performance perspective.     

自悬浮线性空气轴承的理论分析和轴承设计

挤压膜的承载能力已经在理论与实验方面得到了验证,设计了一种新型的挤压膜空气轴承,可应用在直线型导轨系统中;轴承材料为航空铝型材,压电激励和弹性铰链用来引起轴承振动和产生轴承挤压膜的压力,激振频率的选择由轴承的模态主振型确定。通过ANSYS对电．固耦合结构进行的模态分析和谐响应分析,确定了所设计轴承的模态振型和压电激振时的谐响应振型。通过对理论计算和实验结果的比较,证实了此轴承应用于线型导轨的可行性。     

XPG-800型悬挂式胶片冷却机的研制

介绍最新开发的XPG-800型悬挂式胶片冷却机的设计特点、工作原理、主要技术参数、结构特征，阐述了本机组主要技术改进。     

Film Blowing of Layered Silicate Nanocomposites

Bubble formation and stability in the film blowing processing of in situ polymerized and melt-compounded polyamide 6-based layered silicate nanocomposites (LSNs) are correlated to their underlying rheology, structure, and crystallization behavior. The layered silicates enhance melt elasticity, induce γ -form crystallinity, and increase crystallization rates without having any significant effect on the extent of crystallinity. A bubble stability quantification method employed to assess the level of instability during the film blowing process finds the in situ polymerized LSNs to be more stable than PA6, while melt-compounded LSNs do not display such an improved processability. All of the LSN films produced by film blowing possess superior mechanical properties compared to neat nylon 6, despite their relatively rougher film surfaces.     

Polyaniline as a Gas-Sensor Material

Polyaniline (PANI) was synthesized by oxidative polymerization of aniline using ammonium persulfate in an acid medium. The polyaniline salt was converted to base form by treatment with ammonium hydroxide. The polyaniline base was dissolved in N-methyl pyrrolidone (NMP) for film casting. The cast film was doped with HCl for obtaining higher conductivity. Both doped and undoped PANI films were characterized by UV-visible, FTIR, and XRD analyses. The electrical conductivity of the PANI film was studied by a four-point probe method at room temperature. Finally, ammonia gas-sensing characteristics of the prepared polyaniline film were studied by measuring the change in electrical conductivity on exposure to ammonia gas at different concentrations. The influence of concentration of acid during polymerization of aniline and dopant concentration on the gas sensing characteristics of PANI film are reported in this paper.