供应商选择、搜寻策略与企业创新关系研究

利用167家中国制造企业的调查数据,运用层次回归法实证考察了企业不同创新模式下供应商选择、搜寻策略与企业创新的关系.研究表明:无论是效率导向的供应商选择(产品层面或运营层面)还是技术导向的供应商选择都与企业创新(渐进式和突破式创新)表现出显著的正向关联性.进一步研究发现:技术导向的供应商选择与市场搜寻策略相匹配不仅正向作用于企业的渐进式创新,还可以推动突破式创新的产生;而效率导向的供应商选择与关系搜寻策略相匹配主要影响的是企业的渐进式创新.     

初始化类中心的增量K均值法及其在新闻事件探测中的应用

传统的增量k均值法用于事件探测时存在着诸多不足。为了克服其缺陷,本文提出了一种用于事件探测的改进的增量k均值算法(IIKM)。该算法使用密度函数法进行聚类中心的初始化以便客观地选择初始聚类中心,既可以用于在线探测也可以用于回溯探测,并且执行结果受新闻语料被处理顺序的影响较小。本文对有效密度半径和特征空间维数的选择问题进行了讨论,并比较了该方法和Single-pass法及传统的K均值法的性能差异。实验结果表明本文所提出的方法是有效的。     

渐增负荷运动时不同环境条件对血乳酸浓度、血乳酸阈值和血乳酸开始堆积的影响

比较渐增负荷运动时,不同环境条件对血乳酸浓度、血乳酸阈值及血乳酸开始堆积（OBLA）的影响。8名身体健康的男大学生（非热适应者）参加实验,受试者在两种不同温度环境条件下（40和25C）,进行功率自行车渐增负荷运动。研究发现在高温条件下渐增负荷运动时,LT和OBLA发生向左偏移,同时认为在渐增负荷运动时,血乳酸的堆积并不是调节通气量（VE）的唯一因素,而且通气阈值（VT）也不能总是正确地反映LT。     

高校教师评价体系变迁:性质与特征

高校教师评价体系的性质是一种公共合约。改革开放以来我国高校教师评价体系变迁的主要特征就是以高校职能发展、高等教育国际化和国际惯例为导向,以政府为制度供给主体的强制性、渐进式的制度变迁。     

Embedding the dialogic in mixed method approaches to theory development

ABSTRACT

Little attention has been paid to the processes that are involved in making sense of the role dissonance between sources of data has played in the development of theoretical insight. This methodologically oriented investigation considers an unusual set of case exemplars that used mixed methods and dialogic forms of mixing in ways that produced incremental or rupture theorizing. Six of seven used dialogic forms of mixing, including through visual displays, in ways that formatively advanced the analysis. Findings invite readers to consider the advantages of an open and creative approach to mixed methods that embrace the challenges presented by unexpected findings.     

利用互质增量时间戳解决移动代理的重复攻击

重复攻击是移动代理安全问题中很重要的一环,恶意移动代理可能对主机采取重复攻击,从而造成假的认证,严重的会造成系统服务崩溃.通过在移动代理系统中采用互质增量时间戳的机制,能有效地解决移动代理的重复攻击.     

企业知识资本利用与经济效益分析

在重新界定企业知识资本的概念和构成的基础上,利用生产可能性边界理论作为分析工具,对企业知识资本在企业经济增长中的作用机理进行了较深入的分析,并得出了对企业现有知识资本的充分利用和企业知识资本存量的增加是企业经济增长源泉的结论。     

Experimentation in biology lessons: guided discovery through incremental scaffolds

Experimentation is a complex problem-solving process. In biology lessons, experiments involve creative thinking and open discovery; however, they still require some degree of instructional guidance. The right balance between discovery learning and instructional guidance depends substantially on students’ prior knowledge. Students with low prior knowledge in particular might have difficulties with conducting and understanding experiments. Incremental scaffolds might be a valuable tool to meditate between pure discovery and strong guidance while simultaneously taking learners’ individual knowledge and skills into account. In the current study, we examined the effects of incremental scaffolds (IncSc), no scaffolds (NoSc), and worked-out examples (WoEx) on students’ knowledge acquisition while doing inquiry-based experimentation with a special focus on students with low prior knowledge. In a pre-posttest design, 193 students (M_age?=?13.02?±?0.81 years) participated in a four-hour teaching unit on animals’ overwintering strategies. In the pre- and posttest, we assessed the students’ conceptual and procedural knowledge. Our results partially confirmed our hypotheses: Regarding the conceptual and procedural knowledge of all students, incremental scaffolds showed no additional benefit regarding students’ knowledge in the posttest when compared to working with no scaffolds or worked-out examples. For the students with low prior knowledge, working with incremental scaffolds led to higher conceptual and procedural knowledge after the teaching unit than working with worked-out examples.     

基于PID控制的电子节气门设计与仿真

文章主要阐述了电子节气门的结构、工作原理,分析了电子节气门的控制特点以及非线性因素的产生和控制方法。根据电子节气门的工作过程建立了其动力学模型和电路模型。结合数学模型和增量式PID控制的特点设计了电子节气门控制系统,并进行了Matlab仿真。由仿真结果可以看出,电子节气门采用增量式PID控制,具有超调量较小、性能稳定、跟踪效果好、稳态误差小、抗干扰能力强、动静态性能好和可靠性高等优点。     

大变形空间曲梁有限元分析

为了进行空间曲梁大变形有限元分析,将直梁单元位移分量插值的思想改进为位移矢量插值用以建立曲梁单元的位移场,分别建立了适用于任意曲线形式的全拉格朗日和修正拉格朗日增量格式空间曲梁有限元列式.通过采用等参数曲线代替实际曲线的策略,使得修正拉格朗日增量格式曲梁单元可以应用于更广泛的场合.算例对比结果表明,曲梁单元的建立过程正确,曲梁单元的精度要明显高于直梁单元.一般情况下,仅用直梁单元数量1/5的曲梁单元就可以达到相同的计算精度.