网络关系强度与企业技术创新绩效——基于探索式学习和利用式学习的实证研究

 网络强弱关系被视为影响企业技术创新的重要因素,然而简单考察网络关系与技术创新两个变量的相关关系并没有获得一致结论,形成了“关系嵌入性悖论”。以探索式学习和利用式学习为中介变量,提出了网络关系强度对企业突破性创新和渐进性创新的两面性作用的假设,构建了网络关系强度对技术创新影响的概念模型,并进行了实证研究。实证分析结果表明：创新网络关系强度的提高不利于突破性创新,但有利于渐进创新的提升,其中网络关系强度通过探索式学习对突破性创新产生负面影响,但通过利用式学习对渐进性创新产生正面影响。对此做了进一步讨论并提出了未来研究的若干展望。     

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.     

递增强度骑车机械效率与骑车经济性变化规律的研究

目的:研究递增强度运动骑车机械效率与骑车经济性的变化规律。方法:对16名男子自行车运动员进行一次递增负荷自行车测试,计算受试者每级负荷的骑车机械效率和骑车经济性。结果:50%V。O2m ax以下强度运动时,骑车机械效率和骑车经济性随运动强度的增加不断增加;50%V。O2m ax以上强度运动时,骑车经济性随运动强度的增加仍小幅度增加,但骑车机械效率并不随运动强度的增加而增加;80%V。O2m ax以下强度运动时,骑车机械效率和骑车经济性存在高度正相关。结论:骑车经济性随运动强度的增加而增加,但骑车机械效率在进入中等强度后即趋于稳定,可以采用50%~80%V。O2m ax强度运动的机械效率来评价机体的运动效率。     

基于组织学习的战略导向对技术创新的影响

旨在分析不同的战略导向对企业创新模式选择的影响机制,重点进行技术创新相关理论的探究和模型的构建,并在理论分析的基础上提出5个命题。分析表明,技术导向通过提高探索性学习来实现突变创新,市场导向通过采用应用性学习来促进渐进创新,企业家导向则同时通过提高探索性和应用性学习来有效地进行突变创新和渐进创新。     

体育学习中内隐观念与自我妨碍之间关系:成就目标的中介作用

目的：揭示体育学习中内隐观念对自我妨碍的影响，考察成就目标在上述关系中的中介作用。方法：采用问卷调查法对1 236名大学生在体育学习中运动能力信念、成就目标与自我妨碍进行测量。结果显示：（1）在体育学习中，学生的内隐观念对自我妨碍具有显著的预测效应，其中，能力增长观具有负向预测效应，能力实体观则具有正向预测效应；（2）掌握目标可以对自我妨碍产生负向预测效应，成绩回避目标则产生正向影响效应，但成绩趋近目标对学生自我妨碍的影响效应并不显著。（3）在学生的内隐观念与自我妨碍之间的关系中，成就目标存在着显著部分中介效应。能力增长观可通过掌握目标间接减少学生的自我妨碍，能力实体观可通过成绩回避目标间接增加学生的自我妨碍。结论：体育学习中应改变学生动机气氛知觉，避免评价学生的能力，有助于直接或间接减少学生的自我妨碍。     

Test–retest reliability of second lactate turnpoint using two different criteria in competitive cyclists

Abstract

The aim of this study was to determine the relative and absolute reliability of second lactate turnpoint using fixed and individual blood lactate method in competitive cyclists. Twenty-eight male, well-trained cyclists (30.2 ± 10.1 years, 72.0 ± 7.4 kg, 177.3 ± 4.7 cm) were recruited to participate in this study. Cyclists completed two incremental cycling tests to exhaustion over a period of 7 days to determine their peak power output, maximal oxygen uptake, maximal heart rate, maximal blood lactate concentration and two lactate turnpoint criteria. The fixed blood concentration criterion (3.5 mM) and an individual criterion were assessed by a lactate-power curve, considering power output, heart rate and oxygen uptake. The main finding of this study was that both lactate turnpoint criteria showed identical low within-subject variation for power output (2.8% coefficient of variation). High values for test–retest correlations ranging from r = 0.70 to r = 0.94 were found for all variables in both threshold criteria. In conclusion, the individual and fixed method to determine the second lactate turnpoint showed similar high absolute and relative reliability in competitive cyclists.     

Incremental beliefs of ability,achievement emotions and learning of Singapore students

This study investigated the relationships of students’ incremental beliefs of math ability to their achievement emotions, classroom engagement and math achievement. A sample of 273 secondary students in Singapore were administered measures of incremental beliefs of math ability, math enjoyment, pride, boredom and anxiety, as well as math classroom attention and disruption. In addition, students’ end-of-year math achievement scores were collected from school records. The hypothesised mediation model was supported in structural equation modelling analysis. Incremental beliefs of math ability were associated positively with math enjoyment and pride, and negatively with math boredom and anxiety. Achievement emotions fully mediated the relationships of incremental beliefs of math ability to classroom engagement and math achievement. Incremental beliefs of math ability were associated positively with classroom attention through math enjoyment and pride, negatively with classroom disruption through math anxiety and positively with math achievement through the two outcome-related emotions, math pride and anxiety. The findings and implications are discussed in the academic context of Singapore.     

Learning From Examples: Fostering Self-Explanations in Computer-Based Learning Environments

Cognitive skills acquisition involves developing the ability to solve problems in knowledge-rich task domains, and is particularly important for any individual attempting to meet the challenges of our modern, knowledge-driven economy. This type of economy argues for reconceptualizing cognitive skills acquisition as a lifelong process. Research has shown that worked-out examples are the key to initial cognitive skill acquisition and, therefore, critical to lifelong learning. The extent to which learners' profit from the study of examples, however, depends on how well they explain the solutions of the examples to themselves. This paper discusses our own research on different types of computer-based learning environments that indirectly foster self-explanations by (a) fostering anticipative reasoning, (b) supporting self-explanations during the transition from example study to problem solving, and (c) supporting self-explanation activities with instructional explanations. It also discusses ways of leveraging new computer and video technologies to enhance these environments by representing problem situations and their concepts dynamically. The paper concludes by suggesting that these learning environments, if employed successfully, can encourage systematic, lifelong learning.     

递增负荷运动对50～59岁不同脉搏波传播速度人群血管机能影响

目的:研究50~59岁不同脉搏波传播速度人群在逐级递增负荷实验中血管指标的变化,为其有效运动、避免运动风险提供科学依据。方法:以83名50~59岁成年人为研究对象,测定运动中该人群的心率、血压、脉搏波传播速度(brachial-ankle Pulse Wave Velocity,ba-PWV)等血管机能评价指标的变化。结果:(1)ba-PWV1700cm/s人群比ba-PWV1400cm/s人群、1400cm/sba-PWV1700cm/s人群普遍肥胖;(2)ba-PWV1700cm/s人群和1400cm/sba-PWV1700cm/s人群安静状态下收缩压高于ba-PWV1400cm/s人群,具有显著性差异;(3)在递增负荷运动中ba-PWV1400cm/s人群和1400cm/sba-PWV1700cm/s人群舒张压始终在正常范围内,ba-PWV1700cm/s人群在负荷大于100W后舒张压迅速上升,超过正常范围;(4)ba-PWV1700cm/s人群和1400cm/sba-PWV1700cm/s人群在递增负荷实验中均有超过40%的受试者因为血压过高而终止实验。结论:(1)ba-PWV1700cm/s人群多伴有肥胖症状;(2)ba-PWV1700cm/s人群可能会是运动中心血管风险事件的高发人群;(3)ba-PWV1400cm/s人群和1400cm/sba-PWV1700cm/s人群运动中心率、血压上升平稳,上升速率小于baPWV1700cm/s人群;(4)普通人的运动心血管危险可有效的用脉搏波传播速度进行预测,防止运动风险的发生。