长周期光纤光栅包层参数对透射谱影响的数值分析

以耦合模理论为基础,采用三层阶跃折射率光纤模型,导出了长周期光纤光栅透射率、峰值带宽的解析表达式,针对包层折射率和半径变化对透射谱的影响加以数值模拟.结果表明谐振波长位移与折射率的变化基本呈线性关系当包层半径较小时谐振波长位移及透射率的变化均较为明显,反之,其相应的变化则渐趋平缓.     

浅谈金属构件失效分析方法

结合实例介绍了金属构件失效分析中较常用的断口形貌分析、扫描电镜分析、金相组织分析、化学成分分析及人工模拟断口分析等方法.在查找产品的失效原因时,要灵活运用这些方法.     

关于数值分析中插值法教学的研究

数值分析是大学数学系的一门教学中的几个关键问题进行了讨论.在教学过程中,通过对这些问题的分析,不仅能使学生深刻理解插值方法的本质,而且能培养学生的创新能力.     

金属支架药物涂层释放量的比较

临床应用中的PTCA技术,由于金属支架植入后对血管壁的损伤及异物的炎性反应,可引起内膜增生而导致血管内再狭窄.为解决这一难题,采用药物涂层支架进行控制和预防.通过不同的方式对金属支架表面进行药物涂层,并对药物释放量进行比较.     

测量金属线胀系数实验改进

介绍了测量金属线胀系数实验仪的工作原理,对误差产生的原因进行分析,对J-FG3-D型金属线胀系数测量仪进行改进.比较了改进前后的测量结果,发现改进后实验误差降低、精确度提高、改进简单、成本较低,适宜推广.     

城市表层土壤重金属污染分析

通过空间插值法将离散点的测量数据转换为连续的数据曲面,采用内梅罗综合指数法和单因子指数法分析土壤重金属的污染程度;基于物质扩散原理,建立重金属污染物浓度与距离空间关系的偏微分方程,利用最小二乘法拟合出参数,进而确定污染源.另外,考虑地表土壤疏松程度、水体流动这两项来优化模型,从而可以更好地研究城市地质环境的演变模式.     

碱土金属氢氧化物化学性质的热力学分析

用热力学原理对碱土金属氢氧化物的热稳定性、溶解性规律进行了探讨,并指出形成这些规律的热力学原因.     

Numerical analysis of tensile bifurcation phenomenon of a film bonded to a substrate

To study the mechanical properties of the film/substrate structure, the finite element code ABAQUS v6.9-1 is adopted to simulate the tensile mechanical behavior of the nanoscale thin film bonded to a substrate. The bifurcation phenomenon of the structure under uniaxial tension is found: the single-neck deformation, the multiple-neck deformation and the uniform deformation. The substrate and the film are regarded as power-hardening materials obeying the J 2 deformation theory. Firstly, the influence of material hardening match on tensile bifurcation mode is analyzed under perfectly well-bonded interface condition. Then, the effects of interfacial stiffness and other superficial defects surrounding the imperfection on bifurcation mode are investigated. It is concluded that under the well-bonded interface condition, if the stress of the substrate is larger than the film, the film will uniformly deform with the substrate; if the stress of the substrate is smaller than the film, the film will form a single neck, except the case that a weakly-hardening film is bonded to a steeply-hardening substrate when multiple necks can be formed. With the decrease of interfacial stiffness, the uniform deformation mode can transform into the multiple-neck deformation mode, and further transform into the single-neck deformation mode. And other defects surrounding the imperfection can influence the wavelength of deformation and neck number.     

双液滴垂直冲击薄液膜的数值模

The normal impingement process of two water droplets upon a thin film on the solid surface was numerically investigated. The numerical treatment was based on the finite volume solution of the Navier-Stokes （N-S） equations combined with the volume of fluid method （VOF）. Physically reasonable results for the process of two droplets impacting on the thin film were obtained. The effects of the droplet velocity, the fihn thickness and the spacing between the two droplets on the splash and spread process of the impact were examined.     

基于主坐标分析的苏州制造业经济增长趋势面回归预测模型

在经济增长中制造业增长是重要组成部分,影响制造业经济增长的因素很多,在分析时常用多元回归分析方法,但有时建立的回归模型拟合效果不好或不合理。为此文中利用多元统计分析方法中的主坐标分析方法,给出无多重共线性的一组互不相关的主坐标,然后建立趋势面回归预测模型。文中建立了苏州制造业经济增长预测模型,实例表明效果很好。     

Synthesis and structural characterization of a novel metal(Ⅱ)-organic complex based on imidazo[4,5-f]-1,10-phenanthroline

A novel metal(Ⅱ)-organic complex Co(HIMP)(1,4-bdc)·3H2O has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction.The complex is a mononuclear Co(Ⅱ) complex, which is assembled into a 3D supramolecular architecture via strong intermolecular π…π stacking interactions and hydrogen bonds.     

Effects of overburden, rock strength and pillar width on the safety of a three-parallel-hole tunnel

During the excavation of three-parallel-hole tunnel, the tunnel might collapse due to over-stress as a result of inadequate rock pillar width. Treating the rock overburden depth, rock strength, and rock pillar width as variables, a series of 3D numerical analysis was carried out to examine the effect of each variable on the safety of the tunnel, in particular the rock pillar. A stress strength ratio （SSR） was used to define whether the safety of the rock pillar was exceeded. A simple design chart for the case of three-parallel-hole tunnel, which took into account the influence of overburden depth, rock pillar width, and rock strength, was also proposed for used in the preliminary design stage.     

施工企业投标决策的综合分析

工程投标是一项消耗人力、物力、财力和时间的工作，施工企业若不加选择地对多个工程进行投标，一旦不能中标，势必造成企业人、财、物的浪费。本探论了工程投标的多参数决策问题，在主成份分析的基础上，通过选择投标的评价指标和确定各指标的权重，建立投标决策模型与评价标准，以指导施工企业科学投标，并给出了应用实例。     

基于J2EE技术的矿产资源统计系统分析与设计

采用J2EE技术构建了一个矿产资源统计系统。介绍了系统的功能、具体设计思想和实现方法。通过系统重建大大提高了系统的安全性、可靠性、性能,取得了良好的经济效益和社会效益。     

To nail a pudding: metaphorical analysis of the social studies education discourse community on globalization

Despite the abundance of studies on globalization in educational research, globalization is often approached as a monolithic and standardized concept. Focusing on the social studies education in the USA, this study explores how the various metaphors through which globalization is framed embrace particular perspectives on how to conceive and educate about globalization. Specifically, this study discusses seven conceptual metaphors: the global as a place, time, container, spectacle, person, threat, and as a force of nature. In doing so, it illustrates how globalization is predominately rendered as an inclusive structure, a disembedded process, and as a permanent threat. The different metaphors, this paper argues, fulfill a twofold role. First, they define a domain of their own, the global domain, creating a distinctive global viewpoint on human agency and social change. Second, these metaphors also release a political imagination structured around particular expectations of what exactly the global means and does.     

Content analysis of online discussion on a senior-high-school discussion forum of a virtual physics laboratory

In this study we content analyzed the online discussion of several senior-high-school groups on a forum of a virtual physics laboratory in Taiwan. The goal of our research was to investigate the nature of non-course-based online discussion and to find out some useful guidelines in developing such discussion forums for learning purposes. We adapted Henri’s framework and models (1992) for our analysis. The content analysis was conducted in terms of participation rate, social cues, interaction types, and cognitive and metacognitive skills. In this study, we compared the result patterns of two discussion conditions (‘required’ (R-) condition versus ‘non-required’ (NR-) condition) of a non-course-based discussion forum and investigated how the quality of message content changed in the processes of discussion. In the R-condition, participants were required to reply to the thread before they were allowed to read other messages on the forum, whereas participants in the NR-condition were not restricted to this demand. The results showed that for both conditions, the most frequently involved interaction type was ‘direct response’, and the most frequently used cognitive skill was ‘elementary clarification’. Fewer participants of the R-condition strayed from the subject under discussion in comparison to the NR-condition. However, larger percentage of message content containing metacognitive components was found in the NR-condition. When taking the sequences of postings into account, we found that for the R-condition, the percentage of metacognitive component in the message content tended to increase in the up-third postings, whereas for the up-third postings of the NR-condition the percentage of non-cognitive components substantially increased. Overall, the results of our study indicated that the way in which participants used cognitive and metacognitive skills during the discussions was related to the discussion conditions. The initial requirement of reply fostered the use of cognitive skills, but it did not necessarily induce the use of high-level cognitive or metacognitive skills. We concluded that beside the discussion conditions the moderators’ guidance would be influential in determining the quality of online discussion on a non-course-based discussion forum. in final form: 19 August 2005     

略谈英语报刊阅读教学引入批评性语篇分析的作用——以《纽约时报》一则新闻为例

批评性语篇分析认为,语篇是具体化的社会实践.语言为权力服务,语篇体现意识形态.英语报刊阅读课程教材均选自美英报纸杂志.他们所采用的语篇形式和意识形态相伴而行,共同服务于权力.本文以《纽约时报》一则新闻为例,具体论述在英语报刊阅读教学中引入批评性语篇分析,对于帮助学生树立批判性思维,灵活运用语篇分析工具,提高判断和鉴赏能力,直接透视媒体背后所隐藏的动机,从更深的层次解读西方媒体语篇有着重要的作用,并防止被西方媒体潜移默化.     

Understanding the performance of universities to promote technological innovation and transformation: An application to China based on a new network data envelopment analysis cross-efficiency model

When evaluating the performance of Research and Development (R&D) and Scientific and Technological (S&T) transformation activities in universities, the existing studies do not contain prior strategy analysis and inequality analysis. In this regard, prior strategy reflects the relative attention paid by universities to R&D and S&T transformation activities, while inequality analysis assists us in better understanding technological inequality in efficiency across universities. Additionally, this study contributes to the existing literatures by proposing new concepts of window-based cross-efficiency, window-based relative weights and a network Data Envelopment Analysis model. Our framework is able to evaluate the efficiency, perform priority analysis and identify the sources of technological inequality. Empirically, this study focuses on universities in Chinese provinces from 2007 to 2019. This study is of high policy practice, since it provides policy makers with how each university has performed during the examined period and what are the underling factors driving efficiency changes.     

Do developmental mathematics programs have a causal impact on student retention? An application of discrete-time survival and regression-discontinuity analysis

The impact of academic programs—such as developmental mathematics programs—on student retention, has been a controversial topic for administrators, policy makers, and faculty in higher education. Despite deep interest in the effectiveness of these programs in retaining students, scholars have been unable to determine whether such programs have a causal impact on student retention. Rather than assigning students to a developmental program based on a random assignment process as in a true experiment, most of the existing research up to this point has been non-experimental and has focused exclusively on whether student background and demographic characteristics are statistically significant predictors of dropout. Furthermore, prior research is also limited by its reliance on cross-sectional, retrospective designs despite the longitudinal nature of the dropout phenomenon. In this paper, I report the results of a unique piece of research which embeds a regression-discontinuity design within the framework provided by discrete-time survival analysis. By combining these two approaches, I was able to obtain an unbiased estimate of the causal impact of participating in a developmental program in mathematics, and confirm that the risk of leaving college among students who participate in developmental mathematics programs was significantly lower than for equivalent students who did not participate in such programs.     

基于自适应聚类和色差分析的烟草异物在线识别算法研究

提出一种利用聚类和色差分析的烟草异物在线识别算法,采用自适应ISODATA聚类取单元颜色特征,并分析烟叶和异物各分量的分布差异,将单元特征各分量根据直方图分布量化到HIS颜色空间中,从而得到样本学习结果并进行识别。实验结果表明,该算法的平均识别率达到95%,误识率在5%以下。