988 resultados para 160.2540


Relevância:

60.00% 60.00%

Publicador:

Resumo:

The thermal stability, Raman spectrum and upconversion properties of Tm^(3+)/Yb^(3+) co-doped new oxyfluoride tellurite glass are investigated. The results show that Tm^(3+)/Yb^(3+) co-doped oxyfluoride tellurite glass possesses good thermal stability, lower phonon energy, and intense upconversion blue luminescence. Under 980-nm laser diode (LD) excitation, the intense blue (475 nm) emission and weak red (649 nm) emission corresponding to the 1G4 -> 3H6 and 1G4 -> 3F4 transitions of Tm^(3+) ions respectively, were simultaneously observed at room temperature. The possible upconversion mechanisms are evaluated. The intense blue upconversion luminescence of Tm^(3+)/Yb^(3+) co-doped oxyfluoride tellurite glass can be used as potential host material for the development of blue upconversion optical devices.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Using a quasi-natural voting experiment encompassing a 160-year period (1848–2009) in Switzerland, we investigate whether a higher level of complexity leads to increased reliance on trusted parliamentary representatives. We find that when more referenda are held on the same day, constituents are more likely to refer to parliamentary recommendations when making their decisions. This finding holds true even when we narrow our focus to referenda with a relatively lower voter turnout on days on which more than one referendum is held. We also demonstrate that when constituents face a higher level of complexity, they follow the parliamentary recommendations rather than those of interest groups. "Viewed as a geometric figure, the ant’s path is irregular, complex, hard to describe. But its complexity is really a complexity in the surface of the beach, not a complexity in the ant." ([1] p. 51)

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A Confederação Nacional dos Bispos do Brasil (CNBB) apresentou as emendas populares com o maior número de assinaturas até o momento. Elas tratam dos seguintes assuntos: preservação da vida desde a concepção, uso de verbas públicas para escolas públicas e escolas sem fins lucrativos, liberdade de ensino religioso e um último conjunto sobre a ordem econômica. Dom Candido Padim afirma que a reforma agrária é questão fundamental para o atendimento das aspirações populares. Todos os constituintes concordam que as relações no campo devem ser mudadas, mas cada um tem uma visão diferente do problema. O Deputado Virgílio Galassi (PDS-MG) defende uma reforma agrária sem objetivos políticos, mas com inteligência e objetividade para criar novos proprietários rurais. O Deputado Evaldo Gonçalves (PFL-PB) considera que, no Nordeste, uma grande reforma agrária seria realizar programas de irrigação e açudagem. O Deputado Oswaldo Almeida (PL-RJ) diz ser preciso desenvolver uma política agrícola que possa fixar o homem no campo. O Deputado Ulysses Guimarães, Presidente da Assembleia Nacional Constituinte (ANC), anunciou a pauta das sessões extras para tratar dos temas polêmicos. O Deputado Plínio Arruda Sampaio (PT- SP) informa que preferiria que as sessões fossem pela manhã ou pela tarde, para permitir que a imprensa tivesse melhores condições de colher os depoimentos. O Deputado Tito Costa (PMDB-SP) afirma que as sessões extras serão benéficas para o aprimoramento da Constituição.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Executive Summary: The Estuary Restoration Act of 2000 (ERA), Title I of the Estuaries and Clean Waters Act of 2000, was created to promote the restoration of habitats along the coast of the United States (including the US protectorates and the Great Lakes). The NOAA National Centers for Coastal Ocean Science was charged with the development of a guidance manual for monitoring plans under this Act. This guidance manual, titled Science-Based Restoration Monitoring of Coastal Habitats, is written in two volumes. It provides technical assistance, outlines necessary steps, and provides useful tools for the development and implementation of sound scientific monitoring of coastal restoration efforts. In addition, this manual offers a means to detect early warnings that the restoration is on track or not, to gauge how well a restoration site is functioning, to coordinate projects and efforts for consistent and successful restoration, and to evaluate the ecological health of specific coastal habitats both before and after project completion (Galatowitsch et al. 1998). The following habitats have been selected for discussion in this manual: water column, rock bottom, coral reefs, oyster reefs, soft bottom, kelp and other macroalgae, rocky shoreline, soft shoreline, submerged aquatic vegetation, marshes, mangrove swamps, deepwater swamps, and riverine forests. The classification of habitats used in this document is generally based on that of Cowardin et al. (1979) in their Classification of Wetlands and Deepwater Habitats of the United States, as called for in the ERA Estuary Habitat Restoration Strategy. This manual is not intended to be a restoration monitoring “cookbook” that provides templates of monitoring plans for specific habitats. The interdependence of a large number of site-specific factors causes habitat types to vary in physical and biological structure within and between regions and geographic locations (Kusler and Kentula 1990). Monitoring approaches used should be tailored to these differences. However, even with the diversity of habitats that may need to be restored and the extreme geographic range across which these habitats occur, there are consistent principles and approaches that form a common basis for effective monitoring. Volume One, titled A Framework for Monitoring Plans under the Estuaries and Clean Waters Act of 2000, begins with definitions and background information. Topics such as restoration, restoration monitoring, estuaries, and the role of socioeconomics in restoration are discussed. In addition, the habitats selected for discussion in this manual are briefly described. (PDF contains 116 pages)

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Este trabajo ha sido realizado en el marco del Proyecto de Investigación EHU06/116 «Base de datos epigráfica sobre instrumenta doméstica hallados en el País Vasco». Homenaje a Ignacio Barandiarán Maestu / coord. por Javier Fernández Eraso, Juan Santos Yanguas.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

叙述了一个完整的16通道硅基二氧化硅阵列波导光栅(AWG)的设计、制备及测试过程。通道间隔为0.8nm(100GHz),解复用器的插入损耗为16.8dB,其中材料损耗为11.95dB,相邻通道串扰小于一17dB,通道插损非均匀性小于2.2dB。

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A novel design of 100GHz-spaced 16channel arrayed-waveguide grating (AWG) based on silica-on-silicon chip is reported.AWG is achieved by adding a Y-branch to the AWG and arranging the input/output channel in a neat row,so the whole configuration can be aligned and packaged using only one fiber-array.This configuration can decrease the device's size,enlarge the minimum radius of curvature,save time on polishing and alignment,and reduce the chip's fabrication cost.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

给出了更为合理的阵列波导光栅(AWG)的设计原则.在设计时兼顾了输出谱的非均匀性Lu和输出通道数N的要求,克服了设计中可能引起通道数N丢失和不考虑输出谱非均匀性Lu的缺点.用该方法设计了折射率差为0.75%和16×0.8nm的硅基二氧化硅AWG.采用广角有限差分束传播方法(FD-BPM)对所设计的AWG进行了输出谱的模拟,得到了插损为-1.5dB、串扰为-48dB、通道非均匀性约为1dB的AWG,设计指标达到了商用要求。

Relevância:

20.00% 20.00%

Publicador:

Resumo:

对设计的折射率差为0.75%的16×0.8 nm硅基二氧化硅阵列波导光栅(AWG),围绕插损和串扰问题,采用广角有限差分束传播方法(FD-BPM)进行了数值模拟和优化.通过优化在输入波导、阵列波导的喇叭口,得到了插损为1.5 dB、串扰为-48 dB的AWG,优化后的指标已达到商用要求.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

本论文以A~160区奇奇核的高自旋态核结构为研究对象,详细地总结分析了该区奇奇核[h11/2]p[i13/2]n带的性质,利用在束核谱学实验手段布居和测量了166Ta核高自旋态能级结构、借助模型理论对该核实验结果进行分析,还从理论方面系统地研究了A~160区奇奇核[h11/2]p[i13/2]n带的signature反转现象与形变的关系,取得了一些创新成果。 奇奇核高j组态带的signature反转现象系统地存在于A~160、A~130和A~80核区,目前理论上提出的各种可能机制还不能彻底解释清楚这一现象。本文中较详细地归纳了A~160区奇奇核signature反转带,即[h11/2]p[i13/2]n带,实验数据的一些系统学规律,具体贡献在于 1、总结了晕态[h11/2]p[i13/2]n带的跃迁能量系统学规律,指出存在这种规律的原因在于形变和价核子耦合性质随质子数和中子数增减的有规律变化。 2、展示了随质子数增大和中子数减小该带准粒子顺排角动量相加性逐渐变差的现象,指出这种变差的原因可能是形变减小导致剩余n-p相互作用的增强,以及奇奇核带和与之相比较的奇核带形变差异增大。文中强调了使用顺排角动量相加性规则时要考查相加前后两个signature分支顺排角动量的相对大小。跃迁能量系统学规律和顺排角动量相加性规则是目前指定该区奇奇核[h11/2]p[i13/2]n带核态自旋值的有效工具,上述工作有益于研究新核时正确运用这些工具。文中其它归纳和总结工作也为后续研究提供了较为系统的参考资料。 此前尚未有人对166Ta核做过在束研究,我们在中国原子能科学研究院利用HI-13串列加速器通过141Pr(28Si,3n)反应布居和测量了166Ta核高自旋态。实验中使用了5片厚500μg/cm2纯度98.0%的141Pr自衬靶,7台HpGe反康谱仪和1台平面型HpGe探测器。用改变束流能量测量在束单谱和剩余放射性的方法确认实验中生成了166Ta核并为符合实验选定了束流能量。γ-γ符合实验束流能量为127MeV,实验中共收集到约50×106个两重符合事件。实验后用152Eu放射源对探测系统进行了能量和效率刻度。符合实验数据被反演成γ-γ、X-γ和DCO二维谱。通过处理和分析实验数据,得到以下主要结果: 1、用TaKX射线开窗、比较不同束流能量下的在束单谱和排除已知核射线等方法确认了属于166Ta的射线,根据这些射线的级联关系首次建立起了166Ta核的在束能级纲图,其中包括4条转动带,60条射线。166Ta核的晕带是一条耦合性较强的带,建立起的该带能级纲图中包括16条能级和29条射线,每一signature分支有7条E2拉伸跃迁。另外三条带是两条耦合带和一条双退耦带。其中一条耦合带的耦合性较强、位置较高,可能是4准粒子带。 2、计算γ-γ符合矩阵和DCO矩阵开窗谱中峰下面积,得到了166Ta核55条射线在实验中的相对强度Iγ、29条射线的方向关联系数Iγ(35°)/Iγ(75°)和21个核态退激过程的跃迁强度分支比λ等数据。 3、借助模型计算,为实验中发现的4条转动带指定了组态。晕核组态定为9/2[514]p3/2[651]n, Kπ值为6-。另外两条耦合带的组态被定为9/2[514]p3/2[521]n和9/2[514]p3/2[521]n{3/2[651]n}2,退偶带的组态可能是1/2[514]p3/2[651]n。 4、通过分析跃迁能量系统学规律和运用顺排角动量相加性规则指定了166Ta核晕带核态的自旋值,还使用其它方法倾向性地指定了另外三条带的自旋值。 5、提取了一些核态退激过程B(M1)/B(E2)理论值比实验值偏大,指示该带可能存在负γ形变。另外两条耦合带的B(M1)/B(E2)计算值与实验值比较接近,这方面支持我们对其组态的指定。回弯之前的166Ta核晕带B(M1)/B(E2)值与已知的同位素和同中子素奇奇核晕带值相比大许多,我们认为这是组态和形变变化造成的。 6、166Ta和邻核晕带集体转动惯量随转动角频率平方的变化关系显示准质子占据h11/2子壳顶部轨道时顺排发生得较晚,准中子占据i13/2子壳低部轨道时顺排发生得较早。 7、实验结果显示166Ta核的晕带出现signature反转,signature反转点自旋值和反转点之下M1跃迁摆动幅度都与全区规律相符。 我们研究166Ta核的高自旋态能级结构旨在为研究奇奇核signature反转提供新的实验数据,实验研究达到了预期的目的,实验结果证实了在轻Ta奇奇核同位素中也系统地存在signature反转。 在讨论A~160区奇奇核[h11/2]p[i13/2]n带的signature反转机制方面,作者首次利用现有的TRS计算方法系统地考察了该区32个奇奇核该带形变极其随核子数增减的变化趋势,进而通过CSM计算考察了形变对该带signature劈裂的影响。这方面的研究成果主要包括: 1、计算结果显示,该区核芯较容易在γ形变方向受到价核子的形状极化作用,89≤Z≤95时i13/2准中子一般具有正γ形变驱动作用且随着中子数减小此正γ形变驱动作用逐渐增强,67≤Z≤75时h11/2准质子一般具有负γ形变驱动作用且随着质子数增大此负γ形变驱动作用逐渐增强,Z=63和65时h11/2准质子两个signature组态具有不同方向的γ形变驱动作用,总体看h11/2准质子的γ形变驱动作用没有i13/2准中子的强。 2、只考虑ε2和γ形变参量的TSR计算结果显示A~160区中N=89和91奇奇核的[h11/2]p[i13/2]n带有较大的正γ形变,N≥93奇奇核中该带γ形变则较小或为负γ形变。计算出的不同核该带的γ形变值随中子数增加逐渐减小、随质子数变化的规律较复杂且变化幅度没有随中子数变化时那么明显,Z≤67时一些核两signature的形变还有明显的差异。 3、CSM计算表明正γ形变可以导致费米面附近的h11/2准质子轨道signature反转,并且存在正γ形变时ε2形变、ε4形变、质子对力和质子数的不同都对signature反转幅度和反转点对应的角频率都有影响,[h11/2]p[i13/2]n带两个signature组态形变的不同对费米面附近i13/2准中子轨道的位置也有影响。 4、利用从TRS计算出的形变参量所做CSM计算显示,该区部分奇奇核[h11/2]p[i13/2]n带出现signature反转。计算出的signature反转随中子数或质子数变化趋势有些和实验结果相符,也有一些与实验结果不符,对有些实验上发现signature反转的核还计算不出反转。计算结果预言该区一些没有实验数据的奇奇核[h11/2]p[i13/2]n带中也会存在signature反转,这些核是154Eu、162Ta、164Ta和168Re等。 此前对解释A~160区奇奇核signature反转的系统规律时是否必须考虑γ形变还没有定论,本文工作证实了较明显的正γ形变对signature反转起着重要的作用。但是,单纯考虑γ形变并不能完全再现A~160区奇奇核signature反转规律,今后的研究工作还要系统而细致地考虑各方面因素。