热熔压敏胶,用于OPP包装带优先技术

从包装带的历史，成本，生产率，性能（使用温度、对回收纸板粘合性、对非极性基材粘合、涂胶量控制），外观，环境污染问题等方面论证热熔压敏胶作为优先技术，应用于OPP包装带。     

Case study: an investigation into the cause of `error rate drift'

During product development some Hewlett-Packard DDS tape drives experienced a gradual increase in their uncorrected error rate when running a particular operating test at low humidity. This was known as `error rate drift'. A combination of system-level testing, signal processing, and atomic force microscopy showed that the degradation was caused by contamination on the surface of the heads. The `stain' thickness increased each time tape was reused, resulting in progressive attenuation of the readback signal amplitude. Using time-of-flight secondary ion mass spectroscopy the contaminant was identified as inorganic Fe, Si and Al, transferred from the media.     

谈电视节目的制作方式

本文讨论了目前电视节目制作的两种方式,即电视影片和电视录像,井指出它们各自的优势及存在的问题。     

Design analysis of a solid nitrogen cooled “permanent” high-temperature superconducting magnet system

Potential performance advantages of a solid nitrogen cooled “permanent” high-temperature superconducting (SN2/HTS) magnet system over a liquid helium cooled low-temperature superconducting (LHe/LTS) system are explored. The SN2/HTS system design includes a second solid heat capacitor that cools a radiation shield. Recooling of the heat capacitors is performed with a demountable cryocooler. The SN2/HTS system offers both enhanced stability and improved portability over a LHe/LTS system.Design codes are constructed to compare the SN2/HTS system design with a LHe/LTS design for a general permanent superconducting magnet system employing a room temperature bore. The codes predict the system volume and mass that should be expected for a given set of design requirements, i.e. field strength and bore size, and a given set of conductor properties. The results indicate that present HTS conductor critical current and index are not yet sufficient for producing SN2/HTS systems of a size that is comparable with that expected for a LHe/LTS system; however, the conductor properties of Bi2223/Ag have been consistently improving, and new HTS conductors are expected to be developed in the near future. The codes are used to determine the minimum Bi2223/Ag conductor performance required for a SN2/HTS system to be competitive with a LHe/LTS system.     

Failure analysis of leakage current in plastic encapsulated packages

Plastic encapsulated packages exhibit high leakage currents after a few hundred hours in the steam pressure pot test (SPP). The present study investigates two possible causes of leakage current. These are: (a) mold compound, (b) the polyimide tape used for co-planarity of lead frame fingers. The results of this study indicate that the leakage cur-rent is independent of the frame and is not caused by the mold compound. The data indicates that it is the ionic content and acrylic-based adhesive layer of the polyimide tape which cause the leakage current. To eliminate the leakage current, polyimide tape with low ionic content and non acrylic-based adhesive should be used. *Permanent address: School of Physics, Universiti Sains Ma-laysia, 11800 USM Penang, Malaysia.     

Adsorption of Dispersants on Zirconia Powder in Tape-Casting Slip Compositions

This paper reports the extension of the more fundamental work of Tormey et al. on the effectiveness of a common dispersant (menhaden fish oil) and a model system (glycerol trioleate) to tape-casting slip formulation. The adsorption isotherms of the two adsorbates on doped zirconia from methyl ethyl ketone—ethanol solutions were measured by thermogravimetric analysis of solutions equilibrated with the powder surface. Viscosity decreased while sintered density increased in tape-cast samples prepared to dispersant concentrations corresponding to points along the adsorption isotherm in a way which follows the isotherm if binder competition for surface sites is considered.     

轴-径向磁通全超导同步电动机的磁场分析

为了简化传统超导电机的低温冷却系统,提出一种新型轴-径向磁通全超导同步电动机,分析该电机的结构特点和工作原理.利用三维有限元法计算了电机的空载磁场分布,对不同轴向超导励磁绕组下的磁场以及轴向磁路对径向磁路的影响进行分析,分析结果通过空载反电动势实验得到了验证.在样机结构基础上,提出一种新型转子结构方案,分析了2种转子结构下的气隙磁场,并对气隙磁密的谐波含量进行了比较,得出一些有益的结论,为该新型大容量电动机的优化设计和性能分析提供参考.     

自动铺带铺层贴合形成机制

探讨了自动铺带工艺过程中相邻铺层界面间的贴合形成机制,将铺层界面间贴合过程建模为树脂补片在平行板之间挤压流动从而浸润界面的过程。指出在树脂流体黏度一定的情况下,树脂对界面浸润效果越好,则界面贴合能力越强。利用流体力学理论推导出树脂流体对界面浸润效果的计算公式,并分析了铺放压力、铺放速度等因素对浸润效果以及贴合能力的影响,提出以剥离力作为量化铺层间贴合能力的指标。在自行研制的自动铺带工艺参数实验平台上进行了一系列实验,实验结果表明,铺层间贴合能力随铺放速度增大而变差,随铺放压力、模具温度、压辊半径增大而变强,这一规律验证了所提出的树脂流体对界面浸润效果计算公式的正确性。     

桐马环氧玻璃粉云母带在大型发电机上的应用

本文叙述桐马环氧玻璃粉云母带的改进、制作及性能,介绍了采用多胶模压工艺制作的三峡发电机定子线棒各项型式试验在大型发电机定子绕组上的应用.     

超导变压器几种不同绕组形式的环流分析

由于超导材料的零电阻特性,绕组各支路或并绕导线间漏电抗小小的不平衡将会引起很大的环流.环流的存在使得磁场分布更不均匀,进而影响交流损耗和临界电流.本文采用磁场计算与电路分析相结合的方法,即在用有限元法分析磁场并计算反映支路间电磁耦合的电感矩阵的基础上列写电路方程,计算了低压绕组取圆筒式、螺旋式和饼式等三种形式8种情形的环流,并分析了支路电阻对环流的影响.结果表明,仅从减小环流看,圆筒式绕组较螺旋式和饼式绕组更适合具有多根导线并绕的情况;而从减小环流和减少导线焊点考虑,双螺旋式绕组具有优势.同时还证明就环流来说,不能将二次侧圆筒式绕组各层两端短接后用铜线过渡到相邻层来代替绕组轴向并绕导线在层间的换位.