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通过测量一批不同组成的铌酸钾锂晶体的Raman光谱,分析其晶体中组分离子浓度对晶体红外Raman光谱特征的影响,结果表明,晶体中位于C格位的Li浓度对晶体Raman光谱产生了强烈的影响:低Li含量晶体中[NbO6]^7-八面体所对应的3个Raman特征光谱线没有峰发生分裂,在100-400cm^-1范围出现小峰与C格位Li存在相关;当晶体中Li浓度增加时,与v5所对应的Raman峰在散射几何为X(ZY)Z对应的光谱中有所加宽,v2振动模式在两种散射几何中均出现分裂峰,并在100~400cm^-1范围内出现小峰数量增多;当Li浓度接近晶体化学组成时,微扰进一步加强,v5所对应的Raman峰分裂成3个峰,v1和v2振动模式发生部分分裂,在100~400cm^-1范围内小峰更为突出。  相似文献   
2.
本文综述了混合拉曼/掺饵光纤放大器(HFA)的工作原理,结构和特点,介绍了4类HFA基本结构及其实验结果,并通过介绍近年来各类HFA在密集波分复用(DWDM)系统中的应用表明了HFA在带宽,增益和噪声特性方面的优点。  相似文献   
3.
周顺  吴磊  李金利 《价值工程》2013,(27):328-329
本文主要针对矿山井下易发生火灾的情况,提出了采用分布式光纤测温系统对井下"三带"进行实时温度测量,并通过数据统计分析检测温度异常情况来实现火灾预警的方法。  相似文献   
4.
Unlike the corporate sector, detailed estimates of unfunded pension liabilities for most local governments are not available. Thus, prior research on the association between unfunded pension liabilities and municipal creditor decisions (Copeland and Ingram 1983; Marks and Raman 1985) has implicitly assumed that certain pension ratios are good surrogates for municipal pension underfunding. In this paper, we rely on a theoretical model by Ehrenberg (1980) to test empirically the appropriateness of pension ratios as “correlates” of municipal pension underfunding. These ratios were found to be correlated with pension underfunding, although they accounted for only about 30 percent of the variance in the underfunding variable.  相似文献   
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探索纸张本身颜色和印刷品颜色随环境条件变化而变化的规律,对于纸张的使用和保存甚至文物的保存都有一定的意义。实验中选取三种纸张和三原色油墨,通过IGT印刷适性仪进行打样,分别将样条置入氙弧灯老化仪中在一定条件下进行老化后,使用分光光度计对老化前后样条的L*、a*、b*值进行测量,计算得出色差ΔE,并绘出老化时间与色差关系曲线。同时,观察光谱反射率曲线变化,再利用拉曼光谱仪测量其谱图变化。研究结果表明,纸张本身和印品样条在老化前后产生色差,纸张本身的光谱反射率也产生一定变化,而印刷品光谱反射率曲线无明显变化,且纸张分子结构未发生变化,但拉曼强度增强。  相似文献   
6.
This article examines the association between state regulation of accounting practices and municipal borrowing costs. The results demonstrate that stringent accounting regulations do have an effect on borrowing costs after abstracting the effects of other explanatory variables. The direction of the observed effect is difficult to assess due to presence of multicollinearity in the model. However, lower borrowing costs are suggested by the analysis.  相似文献   
7.
Financial theory and empirical evidence suggest that a firm's systematic, or market related, risk is related to its financial conditions. This study empirically investigates the financial determinants of systematic risk for Real Estate Investment Trusts (REITs). The study is an examination of sample of 32 REITs for the period 1976–1978. The results indicate that systematic risk varies directly with financial leverage, business risk, and advisor fee. The explanatory power of the relationship between systematic risk and financial variables exceeds that of previous studies wherein firms were pooled across industry groups. The higher explanatory power observed even with limited data suggests that better estimates of coefficients of financial determinants of systematic risk may be obtained through analysis conducted on an industry by industry basis. Furthermore, such industry-specific analysis provides useful results to practicing financial managers in their financial policy considerations. With the knowledge of how the financial decisions affect the firm's systematic risk, a manager may be able to manipulate those variables so as to reduce the systematic risk for his or her firm and thus increase the market value of the firm's securities.  相似文献   
8.
采用光子转换理论和数值分析方法,研究了采用DCF光纤的喇曼放大器和掺铒光纤放大器组成的混合放大器在DWDM系统中的应用。通过对喇曼光纤放大器的光纤长度、泵浦功率的选择,使得混合放大器的总增益达到一定的平坦度;并分析设计了增益均衡器,让混合放大器最后的总增益达到更高的平坦度。  相似文献   
9.
利用阴极真空弧放电设备制备了表面光滑的类金刚石薄膜材料,通过多波长激发的拉曼光谱研究了不同退火条件下所制薄膜的热稳定性。实验结果表明,在小于400℃的温度处理下,类金刚石薄膜微观结构几乎不发生变化,薄膜处于稳定区;当温度升高至600℃,微观结构开始发生微妙的变化,认为处于亚稳定区;当温度升至800℃甚至1 000℃时,类金刚石薄膜的微观结构发生显著变化,薄膜开始出现石墨化,物理性质不能保持稳定。  相似文献   
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