问与答

问与答问：裸光纤、光纤素线和光纤芯线有什么不同？答：１．裸光纤用预制棒拉制细光纤时，首先要将预制棒加热到高温（约２０００℃），使其变软后进行拉丝。在拉丝时要严格保持预制棒内已形成的折射率分布。对于这种刚刚拉制出来而尚未进行一次涂覆的光纤称为裸光纤。２...     

高湿环境对光纤动态疲劳的影响

为了探究高湿环境对光纤动态疲劳的影响,实验选取多组光纤,分别在高湿和一般环境下采用两点弯曲法测量光纤的动态疲劳。通过对动态疲劳曲线和实验数据进行分析发现,在高湿环境下,光纤所能承受的断裂应力会下降,且测试时的应力速率越高,断裂应力下降越明显,进而影响光纤动态疲劳参数Nd值。     

光纤拉丝机一机两炉的设计改造

改造方案是在原进口中频感应加热炉拉丝机上再加装一台石墨加热炉,使之成为一机两炉工作状态,同时在一台电脑控制下,使用同一拉丝控速系统,可在同一主体设备上分别将大,小直径规格的预制棒拉制成光纤.     

半导体锗芯光纤拉丝过程中的芯-包层流速差异研究

半导体芯光纤因其特殊的光电特性而受到广泛关注。由于纤芯和包层材料之间的性质差异,制备高质量的半导体芯光纤比传统掺杂石英玻璃光纤更为困难。以锗芯光纤为研究对象,通过有限元法,模拟仿真了激光拉制锗芯光纤的动态过程,研究了拉制过程中芯层锗和包层石英玻璃材料的流速差异,以及不同拉丝速度对其流速差异的影响。仿真结果表明:在预制棒颈缩区,芯层锗和包层石英玻璃材料的流速差异最大,且不同拉丝速度对预制棒芯层锗和包层石英玻璃材料的流速影响不同。     

拉丝条件对光纤折射率的影响

针对光纤预制棒及其拉制的光纤折射率分布测量结果的差异,分析了造成这种差异的原因是拉丝条件的不同,于是提出在拉制光纤时必须严格控制工艺,确保光纤性能一致性。     

美国电话电报公司研制出新的光纤涂层法

在新奥尔良(New Orleans)最近召开的光纤通信会议上宣布,新泽西州霍普韦尔(Hopwell.New Jersey)的美国电话电报中心的究研者们研制出一种以12米/秒速度拉制和涂覆光纤的新方法,而光纤的机械特性和光学性能和用一般拉丝速度所形成的相同。负责研制该工艺的研究者Un-Chul Paek及其助手Charles M.Schroeder采用一座高大拉丝塔,在用同聚合物涂覆的同时拉制出大长度光纤。拉丝过程中,光纤直径始终受到监控,以保持均匀的直径。在7公里单层涂覆     

新型激光加热基座生长法生长氧化锆单晶光纤

为了拉制氧化锆单晶光纤,采用一种基于激光加热基座生长法的单晶光纤拉制系统,在原有的激光加热基座生长法生长单晶光纤的基础上,设计出环形聚焦激光加热系统,对其光学系统进行了改进、优化.利用椭球镜的双焦点特性设计光路,在其第一焦点处形成聚焦环形热源,用于熔化晶棒,拉制光纤;通过ZEMAX光学软件对系统进行了光学仿真.结果表明,在光学系统的聚焦点,能形成高质量的环形热源.该系统有着其它激光加热基座生长法的光学系统无法比拟的优点,在拉制氧化锆和其它高温单晶光纤方面有着很好的应用.     

大尺寸光棒高速拉制技术的精细化探索

通过对光纤拉制工艺进行改进,将高温炉、送棒系统、冷却系统、固化系统和收丝系统进行适应性改进,并严格拉丝过程控制,烽火通信在大尺寸光棒高速拉制技术方面进行了精细化改善的有益探索,实现了长达2m,直径达150mm以上的大尺寸光纤预制棒的高质量拉制,可实现一次性稳定拉制光纤长度达到2500km的水平,有力提升了光纤的产出效率,大幅提高了光纤的产品质量。     

两种光纤动态疲劳参数测试方法的比较

光纤拉伸强度的测量对于理解其裂纹扩展、疲劳性能以及老化效果很重要,有助于预测其长期行为。针对光纤引入最新一代涂层后,在测量光纤拉伸强度过程中遇到一些与试验相关的问题,通过对比拉伸法和两点弯曲法对光纤动态疲劳参数nd的测试结果,建议对于一次涂层原位模量较低的涂层体系涂覆的光纤较适宜采用两点弯曲法测试其动态疲劳性能。     

高强度光纤的制备(综述)

光纤的大长度抗拉强度是确定在成缆和使用环境下沿光纤长度上允许应力水平的重要参数。为了达到高的生产率和满足某些系统对光纤机械强度的要求,开发大长度高强度光纤是必须的。本文综述了获得大长度高强度光纤所必须满足的原材料、工艺环境、拉丝设备、被复技术等条件,简单介绍了国外对耐疲劳光纤研究的动态。     

利用3D-PDA系统对四角切燃锅炉炉膛上部的气固两相流场冷态测量研究

四角切烯锅炉是我国电力行为中应用最广泛的炉型。本文在冷态模型实验台上，要用三维激光相位多普勒动态粒子分析仪（３Ｄ－ＰＤＡ），针对正常工况和一次风微量反旋偏转技术工况，测量了炉膛上部气固两相流场，得出了较准确、全面的气固两相流场数据，并对炉膛上部气固两相流场特点进行了描述，对炉膛对流受热面烟道的烟温偏斜原因作出分析。本文的工作为调整炉膛上部气固两相流场、改善炉膛对流爱热面烟道烟温及烟气流量偏斜提供了     

用QCM分析ZnO纳米线在湿度检测中的响应

研究石英晶体微天平传感器上涂敷纳米ZnO膜,实现对湿度检测。实际测试结果涂敷纳米ZnO膜的石英晶体传感器在一定湿度范围的输出频率随测试的相对湿度变化。研究结果表明在湿度检测中,相对湿度越高,响应时间越长;涂敷膜越厚,频率变化越大,在相同的湿度下(高湿度)响应时间越长。     

SnO_2-LiZnVO_4系湿敏元件电容特性分析

采用共沉淀法制备SnO2-LiZnVO4系湿敏材料,研究了LiZnVO4的掺杂量对材料湿敏电容的影响。结果表明:LiZnVO4的掺杂量,环境的相对湿度(RH)、测试信号频率对湿敏电容有较大影响。当x(LiZnVO4)为10%时,可使材料具有合适的低湿电容和灵敏度。在100Hz下,当环境的RH从33%上升到93%时,SnO2-LiZnVO4系湿敏材料制备的湿敏元件的电容增量可达起始值的2300%,显示出较高的电容湿度敏感性。湿敏元件的电容响应时间约为54s,恢复时间约为60s。湿滞约为RH6%。     

Fatigue behavior of multifilamentary BSCCO 2223/Ag Superconducting tapes

The mechanical properties and the critical current were studied in three commercial multifilamentary Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10+x//Ag tapes subjected to monotonic and fatigue tension at 77 K in the longitudinal direction. It was found that transport properties were not compromised under monotonic tension if the maximum tensile stress remained below the conventional 0.2% yield strength. This magnitude was reduced by 10% to 20% in the case of fatigue loading, and the service life of the tape was dictated by the mechanical fatigue life.     

Environmental aging and deadhesion of siloxane-polyimide-epoxy adhesive

Adhesives are subject to environmental aging that degrades their strength and fracture toughness over time. Aging increases the rate of crack growth under fatigue loading, and can lead to deadhesion of an adhesive bond. In this study, an empirical model is constructed from peel test data that quantifies the rate of aging of a siloxane-polyimide-epoxy adhesive as a function of temperature and humidity exposure. An accelerated test methodology that accounts for both aging and fatigue is then proposed, and demonstrated using a case study.     

Study on fatigue life and electrical property of COG assembly under thermal–electric–mechanical coupled loads

It is well-known that chip-on-glass (COG) assembly is often subjected to the coupled effects of temperature, electrical current and cyclic mechanical loading in service. Therefore, the fatigue life and electrical property of COG assembly undergoing thermal–electric–mechanical coupled loads have been studied in the present work. Based on the present investigations, it was found that that the relative resistance of COG assembly in the fatigue process displayed different trends according to environmental temperature and mechanical loading amplitude. Moreover, the fatigue life of the COG assembly decreased with the increased temperature and the increased loading amplitude. Finally, the Basquin's equation can predict the fatigue life of COG assembly at different environmental temperatures well.     

深埋地下工程室内热环境特点的模拟研究

主要根据室内热湿负荷大小和一般送风设计参数的规定,通过改变空调的送风参数,模拟并分析深埋地下工程空调房间的热环境特点。对模型房间同一垂直截面不同工况下的温度场和湿度场进行了模拟,结果表明,垂直温差都不超过1℃,不会对热舒适产生明显的影响,湿度设计达到要求。     

An investigation on aging of multifilamentary 2223-BSCCO specimensunder mechanical and environmental stresses

The effect of mechanical, thermal, and environmental stresses on specimens of multifilamentary 2223-BSCCO tapes, fabricated by the powder-in-tube technology, is discussed in this paper. Short-term and long-term (aging) tests were performed for the purpose of evaluating the strength and endurance of the specimens under compression, tensile, and vibration stresses and In combinations or temperature and humidity. The diagnostic properties employed to evaluate material behavior and degradation are critical current and quantities associated with hysteresis loops. It is shown how mechanical stresses can affect specimen performance in light of application to cables for energy transport. In particular, the endurance lines under tensile and vibration stresses are drawn, achieving indexes useful for evaluation of superconducting tapes and cable design     

Investigation of interfacial delamination of a copper-epoxy interface under monotonic and cyclic loading: experimental characterization

Interfacial delamination is of important concern for multilayered microelectronic packaging structures, as it is one of the most common failures observed in microelectronic packages. To predict interfacial delamination propagation under both static and cyclic loading, one needs to characterize interfacial properties. Key parameters for characterizing an interface include interfacial fracture toughness, interfacial fracture resistance, onset of delamination from an initial interface crack, and fatigue crack propagation (FCP) rate. The objective of this study is to experimentally investigate the interfacial properties of a copper-epoxy interface. Such an interface is one of the most common features seen in multilayered integrated substrates. Amenable to thin film process, sandwich double cantilever beam (DCB) specimens have been designed and fabricated in clean-room environment. Standard tensile tests have been preformed for determining the interfacial fracture toughness and, with monitoring the crack length against the applied force, interfacial fracture resistance. Fatigue tests have also been conducted in studying the onset of delamination from an interfacial delamination starter and the follow-up fatigue crack propagation (FCP) of an interfacial crack along the copper-epoxy interface.