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The configuration of the novel three-stage L-band erbium-doped fiber amplifier with very large and flat gain and very low noise figure presented in this paper uses the forward ASE (amplified spontaneous emission) from the first section of the EDF (erbium-doped fiber) and the backward ASE from the third section of the EDF (both serve as the secondary pump sources of energy) to pump the second EDF. To improve the pump efficiency, the power of the pump is split into two parts (with a ratio of e.g. 2:7). The characteristics of this L-band EDFA are studied on the basis of the Giles Model with ASE. 相似文献
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提出了一种基于由热扩芯光纤构成的马赫-曾德干涉滤波器的新型多波长可调谐环形腔掺铒光纤激光器.马赫-曾德干涉滤波器由一段掺镱光纤和两根实验室自制的热扩芯光纤熔接而成.当马赫-曾德干涉滤波器中的掺镱光纤受到980 nm激光二极管泵浦时,滤波器的干涉条纹将向长波长方向漂移.利用该可调谐滤波器构建一个环形腔掺铒光纤激光器,获得了11个激射波长同时输出,每个激射波长的信噪比都超过40 dB.通过改变掺镱光纤的泵浦功率,激光器的激射波长可调. 相似文献
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马晓明 《深圳职业技术学院学报》2002,1(2):7-13,59
利用速率方程模型,对980nm泵浦带光隔离器的两段型掺铒光纤放大器(EDFA)的性能进行了研究,分析了增益、噪声系数、输出信号功率与泵浦光功率、输入信号光功率等参数之间的关系,结果表明小信号增益至少可提高3dB,噪声系数降低1.0dB,接近量子极限噪声系数。 相似文献
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饶丰 《海南师范学院学报》2006,19(1):38-41
提出了一种由高折射率纤芯／波导层／金属薄膜包覆层／被检测物层构成的四层结构表面等离子共振光纤生物传感器．对其研究发现：这种传感器能够很好地感应待测物的折射率，与三层薄膜结构光纤SPR传感器相比其衰减峰非常尖锐，这说明其损耗小且分辨力高，适合长距离、高精度、高分辨力场合的测量，对生物医学中的免疫反应实时检测及表面显微技术的研究具有重要的意义． 相似文献
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The goals of the study were first to compare the social and academic well-being (loneliness and academic self-efficacy (ASE) among college students with and without learning disabilities (LD), as well as three personal strengths (hope, optimism and sense of coherence (SOC). The second goal was to identify the predicting factors to their loneliness and ASE. The sample consisted of 178 female students from the special education programme in a teachers’ college, divided into two subgroups: 59 students with LD and 119 students without LD. The following questionnaires were used: the loneliness scale; ASE; Internet and smartphone activities; hope, optimism and SOC. As expected, students with LD reported higher levels of loneliness and lower levels of ASE. Multiple hierarchical regression analyses showed that the use of the Internet for avoidance coping was a significant predictor for the loneliness and ASE. Results of the mediation analysis further demonstrated that LD was positively associated with online avoidance coping. However, hopeful thinking had a significant mediation effect between LD and online avoidance coping. Students with LD who have hopeful thinking were less engaged in avoidance coping than their peers, focusing attention on the importance of hope as a mediation factor. 相似文献
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A novel quantum dots (QDs) optical fiber amplifier was proposed and demonstrated. It was fabricated by dipcoating the PbSe
QDs doped sol onto the taper region of fiber coupler. The PbSe QDs was synthesized according to a colloidal method. A lower
refractive index sol was also synthesized as the host of PbSe QDs. A standard single mode fiber was used to make the fusion
tapered fiber coupler which had double input and output ports. With the simple structure, a signal and a pump can be injected
into the amplifier and excite the PbSe QDs through evanescent wave. The experimental results indicated that the amplified
light wave was observed at 1 550 nm wavelength with 980 nm wavelength laser diode as pump. 相似文献
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Andrea Mühlenweg Dorothea Blomeyer Holger Stichnoth Manfred Laucht 《Economics of Education Review》2012,31(3):68-76
We identify effects of age at school entry (ASE) on the development of child temperament. Our analysis is based on psychometric measures from a longitudinal cohort study of children in the Rhine-Neckar region in central Germany. In children with a higher ASE due to a birthday late in the year, we find more favorable outcomes with respect to several temperamental dimensions: these children are more persistent and less often hyperactive. The findings are robust if we control for the respective temperamental dimension before entering school. We also show that the ASE effect on persistence is stable over time by comparing the children at age eight and age eleven, after the children have entered Germany's segregated secondary-school tracks. At age eleven, we additionally find significant ASE effects on adaptability to change. Overall, the results point to a high degree of malleability in the considered non-cognitive skills after school entrance. By contrast, we do not find a significant effect of ASE on cognitive skills as measured by IQ. 相似文献
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沈俊慧 《福建工程学院学报》2014,(6):589-594
文章以EDF算法为基础,提出一种改进的调度算法IEDF。在IEDF中,提出一种新的带宽调度策略,并在3种具体情况下进行业务流调度过程分析。同时,在SIM环境下进行仿真实验,仿真结果表明,和原EDF算法相比,IEDF算法有效保证了带宽,降低了时延,提升了Qos。 相似文献
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为研究DSF光纤参量放大器(DSF-FOPA)的带宽增益特性,利用四波混频功率耦合方程进行分析,并对相位匹配条件进行了讨论.在小信号条件下,采用对称抽运时,得到了不同参数对放大器的带宽和增益的影响情况.分析结果表明,采用大的抽运功率、短的DSF光纤及宽的波长间隔可以拓宽放大器的带宽. 相似文献
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AbstractSome resilient students with LD succeed ‘against the odds’ and reach college. The goals of the study are to explore their resources and barriers during their studies. The relationships between academic self-efficacy (ASE) and personal resources (sense of coherence (SOC) and hope) among college students with learning disabilities (LD) will be examined. The sample consisted of 438 college students divided into two subgroups: 149 students with LD and 289 Non-LD students. Results indicated that college students with LD reported lower levels of ASE, as well as lower levels of hope subscales and SOC. Persistent challenges of early learning distress experienced by those students during school periods continue to be prevalent during their college years. The ASE was predicted by the personal resources, and the risk factor (tiredness lost its significance). The importance of personal resources (SOC and hope subscales) was further emphasised by the mediation model (PROCESS). They mediated the relationships between LD and ASE. These outcomes call for empowering interventional programmes in order to promote hopeful thinking and personal coherence. 相似文献
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Shazia K. Jan 《The American journal of distance education》2013,27(1):30-40
This study investigated the relationships between academic self-efficacy (ASE), computer self-efficacy (CSE), prior experience, and satisfaction with online learning and explored how ASE, CSE, and satisfaction vary with age and gender. One hundred and three graduate students enrolled in purely online courses in January 2014 at a university in the midwestern United States participated in the survey. Scales with known reliability were used to measure ASE, CSE, and satisfaction. The study showed a significant positive correlation among all the variables except CSE and satisfaction. Regression analysis showed ASE to be most predictive of satisfaction with online learning. Females had a higher mean ASE than males, and participants aged thirty-five years and above had a higher mean CSE than younger participants. 相似文献
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黄丹芸 《泉州师范学院学报》2009,27(2):1-4
对一类组合设计中的外差族进行研究,利用分圆方法构造外差族,考虑在分圆类中取出若干个判别能否构成外差族,主要是4阶以及6阶分圆类的情况,并得到几类外差族． 相似文献
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INTRODUCTION Traditionally, in real-time schedule theory,real-time requirements are classified into two types,hard real-time (HRT) and soft real-time (SRT)(Giorgio, 1997). HRT requirement is mainly util-ized in temporal safety-critical applications on thetemporal aspect of processing a task. For applica-tions with HRT requirement, such as process con-trol or manufacture automation, deadline miss isnot tolerated, i.e., each task of an HRT applicationmust meet its deadline, and ot… 相似文献
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(m,k)-firm real-time or weakly hard real-time(WHRT)guarantee is becoming attractive as it closes the gap between hard and soft(or probabilistic)real-time guarantee,and enables finer granularity of real-time QoS through adjusting m and k.For multiple streams with(m,k)-firm constraint sharing a single server,an on-line priority assignment policy based on the most recent k-length history of each stream called distance based priority(DBP)has been proposed to assign priority.In case of priority equality among these head-of-queue instances,Earliest Deadline First(EDF)is used.Under the context of WHRT schedule theory,DBP is the most popular,gets much attention and has many applications due to its straightforward priority assignment policy and easy implementation.However,DBP combined with EDF cannot always provide good performance,mainly because the initial DBP does not underline the rich information on deadline met/missed distribution,specially streams in various failure states which will travel different distances to restore success states.Considering how to effectively restore the success state of each individual stream from a failure state,an integrated DBP utilizing deadline met/missed distribution is proposed in this paper.Simulation results validated the performance improvement of this proposal. 相似文献
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针对混合任务实时调度的需求和现有混合任务实时调度算法的局限性,提出了一种长释放时间间隔优先的混合任务实时调度算法LRIF,该算法采用固定优先级和动态优先级相结合的调度策略,根据非周期性软实时任务作业到达流分布,将一定比例的软实时任务作业当作硬实时作业调度,除了可对周期性硬实时任务提供调度保证外,同时还可确保非周期性软实时任务的可调度率.还提出了LRIF调度算法的可调度性分析方法,并讨论了LRIF调度算法的实现方法.测试结果表明:LRIF调度算法具有更好的调度性能,可有效调度由周期性硬实时任务和非周期性软实时任务构成的混合实时系统. 相似文献
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张婷 《实验室研究与探索》2008,27(9)
介绍了北京理工大学自动化系统工程师技能培训与测试中心(ASE)建设情况,分析了现代自动控制系统的特点与结构体系,提出了ASE对知识结构和技能培训的基本要求,着重阐述了运动控制系统工程师技能培训方案及其考核测试方法。 相似文献