Active temperature compensation design of sensor with fiber gratings

A technique for compensation of temperature effects in fiber grating sensors is reported. For strain sensors and other sensors related to strain such as electromagnetic sensors, a novel structure is designed, which uses two fiber Bragg gratings (FBGs) as strain differential sensor and has temperature effects cancelled. Using this technique, the stress sensitivity has been amplified and gets up to 0.226 nm/N, the total variation in wavelength difference within the range of 3-45 °C is 0.03 nm, 1/14 of the uncompensated FBG. The structure can be used in the temperature-insensitive static strain measurement and minor-vibration measurement.     

初露端倪的DNA计算机

 电子计算机从诞生的1946年到今天,不过半个世纪,发展速度之快令人感叹!据统计,每隔5～8年,计算机的运算速度提高10倍,体积缩小90%,成本降低90%.     

光敏药物与激光治癌

 “癌魔”作乱于人世已有它漫长的历史,近年似乎更为猖獗.世界许多国家曾大量耗资与“癌魔”宣战,其结果如何?大量事实证明进展甚微,“癌魔”的幽灵依然在世界各地游荡.然而,光敏药物与激光的出阵,为人们战胜“癌魔”提供了新的希望.     

多目标决策在技术经济分析中的应用

在技术经济分析中常常碰到这样一类问题:如何从所有备选方案中选出使纯经济效益指标与经济效率指标同时达到最优的方案。本文把这类问题归结为多目标决策问题,并且建立了相应的数学模型及其求解方法。     

用多元分析方法评价企业经济效益的初探

目前我国对企业经济效益的评价与改核常常只用一两个效益指标(如固定资产净值、利税总额),这种方法不能全面反映企业的经营情况。本文用主成分分析和因子分析法,结合实例作出全面评价企业经济效益的尝试,同时利用逐步聚类分析法根据企业的主要效益指标给出企业的等级划分办法。一样本数据的收集说明我们在贵州省大中型企业中选取了20个企业作为样本,主要的经济效益指标是:x_1为平均每一职工创造工业净产值(元);x_2为平均每一职工实现产品销售收入(元);x_3为百元物耗     

Tl_4Ba_3Ca_3Cu_4O_y系统的超导电性和磁化反常

Tl_4Ba_3Ca_3Cu_4O_y 氧化物超导体中存在100K 和120K 两个超导相.测量电流为10mA 时,零电阻超导 T_c 为119K.DC 磁化结果表明:在77K 时不可逆场约为2200O_e,冻结磁通密度11.6G,样品是弱钉扎Ⅱ类超导体.Meissner 效应测量结果表明:Meissner 信号的61%是120K 相的贡献,39%是100K 相的贡献.超导体积的上限和下限的比较,不同磁场和测量电流的 R(T)超导转变以及磁化反常表明:我们的样品中存在着大量的弱连接超导电性,并构成邻近效应超导体,研究了它的日 H_(c2)(T).并由邻近效应超导体的磁化曲线演算出它的超导参量.     

A novel dual-wavelength fiber Bragg grating and its application in fiber ring laser

A novel method for fabricating dual-wavelength fiber Bragg gratings (FBGs) by using one phase mask is developed. The method is based on a double-exposure technique. Our technique lends itself to writing gratings with controllable reflectivity and separation of two Bragg wavelengths. A grating with two equal transmission peaks of 20.25 dB is obtained by this method and the separation of the two Bragg wavelengths is about 0.8 nm. With the grating, we demonstrate a dual-wavelength erbium-doped fiber ring laser whose interval of the two peaks is 0.8 nm. The laser's peak powers can get 3.1 mW above and have a good stability.