Directed collaboration patterns in funded teams: A perspective of knowledge flow     

《Information processing & management》2023,60(2):103237

Collaborations in funded teams are essential for understanding funded research and funding policies, although of high interest, are still not fully understood. This study aims to investigate directed collaboration patterns from the perspective of the knowledge flow, which is measured based on the academic age. To this end, we proposed a project-based team identification approach, which gives particular attention to funded teams. The method is applicable to other funding systems. Based on identified scientific teams, we detected recurring and significant subgraph patterns, known as network motifs, and under-represented patterns, known as anti-motifs. We found commonly occurred motifs and anti-motifs are remarkably characterized by different structures matching certain functions in knowledge exchanges. Collaboration patterns represented by motifs favor hierarchical structures, supporting intensive interactions across academic generations. Anti-motifs are more likely to show chain-like structures, hindering potentially various knowledge activities, and are thus seldom found in real collaboration networks. These findings provide new insights into the understanding of funded collaborations and also the funding system. Meanwhile, our findings are helpful for researchers, the public and policymakers to gain knowledge on research(ers) evolution, particularly in terms of primordial collaboration patterns.  相似文献   

“流空间”视角下粤港澳大湾区空间布局分级特征研究   总被引：1，自引：0，他引：1  

杨思蓓  胡志华 《上海海事大学学报》2020,41(1):93-99

为加快粤港澳大湾区区域一体化进程,基于“流空间”视角,以粤港澳大湾区11个核心城市为研究对象,从客运流、经济流、信息流三个维度建立数理统计模型,分析粤港澳大湾区的交通、物流和经济信息化水平,并综合运用Jenks自然断裂点法和Moran散点图对粤港澳大湾区进行空间布局分级特征研究。研究结果表明:粤港澳大湾区有两个增长极——广州和深圳;粤港澳大湾区以珠江为界,珠江东西两岸分级明显;港珠澳大桥的连通有助于加强流要素空间互动,发挥更强的区域辐射和带动作用,扩大H-H连绵区的分布范围。  相似文献   

液滴撞击凹凸槽道表面液膜的动态演变     

周鑫  王宏  朱恂  陈蓉  廖强  丁玉栋 《中国科学院大学学报》2020,37(2):255-262

为研究固体表面结构对液滴撞击液膜后演变行为的影响规律，采用CLSVOF方法模拟液滴撞击不同尺寸槽道上的表面液膜的流动过程，获得不同槽道高度和宽度时液滴撞击液膜后的演变行为，探索撞击速度、液膜黏度和表面张力对撞击后液膜铺展行为、水花飞溅高度和二次液滴形成的影响。结果表明，槽道结构对液滴撞击液膜后的动态行为具有显著影响，随着槽道高度的增加，冠状水花厚度越薄，越容易产生二次液滴；随着液膜黏度的增大，则抑制冠状水花形成与二次液滴的产生；液膜表面张力减小时，射流更加明显，二次液滴数更多，飞溅现象提前，冠状水花消失时间延后。  相似文献   

低负荷加压训练改善自发性高血压大鼠的血压效果及机制研究     

谭朝文  赵彦  俞莹莹  马晓缓  郑玉婵 《体育科学》2020,(3):46-53,63

目的:探究低负荷加压训练对自发性高血压大鼠的降压效果及其作用机制。方法:选取4周龄雄性自发性高血压大鼠,随机分为对照组(高血压安静组)、低负荷训练组、低负荷加压训练组和高负荷训练组。低负荷训练组进行35%~55%1RM递进式低负荷爬梯训练,低负荷加压训练组进行30%~40%血流受限结合35%~55%1RM递进式低负荷爬梯训练,高负荷训练组进行55%~75%1RM递进式高负荷爬梯训练,训练后测定血压、血液中内皮素-1、血管内皮生长因子、一氧化氮合成酶的表达和心肌组织中内皮型一氧化氮合成酶的表达。结果:1)与对照组、高负荷训练组相比,低负荷加压训练组收缩压、舒张压显著下降(P<0.05);与低负荷训练组相比,低负荷加压训练组舒张压显著下降(P<0.05)。2)与对照组相比,低负荷加压训练组血液中内皮素-1表达显著下调(P<0.05),血管内皮生长因子和一氧化氮合成酶表达显著上调(P<0.05);3)与对照组相比,低负荷加压训练组心肌中内皮型一氧化氮合成酶表达显著上调(P<0.05);4)在低负荷加压训练组中,收缩压与内皮素-1呈正相关,相关性分析具有统计学意义(P<0.05);收缩压与一氧化氮合成酶、血管内皮生长因子、内皮型一氧化氮合成酶均呈负相关,相关性分析具有统计学意义(P<0.05)。结论:1)低负荷加压训练降压效果优于高负荷训练;2)低负荷加压训练能够通过下调血液中内皮素-1的表达,上调血液中血管内皮生长因子和一氧化氮合成酶的表达,同时上调心肌中内皮型一氧化氮合成酶表达,改善内皮细胞功能,达到降压的效果。  相似文献   

Combined effects of exposure to hypoxia and cool on walking economy and muscle oxygenation profiles at tibialis anterior     

Masahiro Horiuchi  Yoko Handa-Kirihara  Daijiro Abe  Yoshiyuki Fukuoka 《Journal of sports sciences》2019,37(14):1638-1647

We investigated combined effects of ambient temperature (23°C or 13°C) and fraction of inspired oxygen (21%O₂ or 13%O₂) on energy cost of walking (C_w: J·kg^?1·km^?1) and economical speed (ES). Eighteen healthy young adults (11 males, seven females) walked at seven speeds from 0.67 to 1.67 m s^?1 (four min per stage). Environmental conditions were set; thermoneutral (N: 23°C) with normoxia (N: 21%O₂) = NN; 23°C (N) with hypoxia (H: 13%O₂) = NH; cool (C: 13°C) with 21%O₂ (N) = CN, and 13°C (C) with 13%O₂ (H) = CH. Muscle deoxygenation (HHb) and tissue O₂ saturation (StO₂) were measured at tibialis anterior. We found a significantly slower ES in NH (1.289 ± 0.091 m s^?1) and CH (1.275 ± 0.099 m s^?1) than in NN (1.334 ± 0.112 m s^?1) and CN (1.332 ± 0.104 m s^?1). Changes in HHb and StO₂ were related to the ES. These results suggested that the combined effects (exposure to hypoxia and cool) is nearly equal to exposure to hypoxia and cool individually. Specifically, acute moderate hypoxia slowed the ES by approx. 4%, but acute cool environment did not affect the ES. Further, HHb and StO₂ may partly account for an individual ES.  相似文献   

Effects of periodic carbohydrate ingestion on endurance and cognitive performances during a 40-km cycling time-trial under normobaric hypoxia in well-trained triathletes     

Yi-Hung Liao  Toby Mündel  Yan-Ting Yang  Chen-Chan Wei  Shiow-Chwen Tsai 《Journal of sports sciences》2019,37(16):1805-1815

The purpose of this study was to examine CHO ingestion on a cognitive task using a field-simulated time-trial (TT) under hypoxia in well-trained triathletes. Ten male triathletes (age: 22.1 ± 1.1 years; VO₂max: 59.4 ± 1.4 ml/kg/min) participated in this double-blind/crossover/counter-balanced design study. Participants completed 3 TT trials: 1) normoxic placebo (NPLA; FiO₂ = 20.9%), 2) hypoxic placebo (HPLA; FiO₂ = 16.3%), and 3) hypoxic CHO (HCHO; 6% CHO provided as 2 ml/kg/15 min; FiO₂ = 16.3%). During the TT, physiological responses (SpO₂, HR, RPE, and blood glucose/lactate), cognitive performance, and cerebral haemodynamics were measured. Hypoxia reduced TT performance by ~3.5–4% (p < 0.05), but CHO did not affect TT performance under hypoxia. For the cognitive task, CHO slightly preserved exercise-induced cognitive reaction speed but did not affect response accuracy during hypoxic exercise. However, CHO did not preserve the decreased Hb-Diff (cerebral blood flow, CBF) and increased HHb in the prefrontal lobe (p < 0.05) during hypoxic exercise, and CHO failed to preserve hypoxia-suppressed prefrontal CBF and tissue oxygen saturation. In conclusion, the present study demonstrates that CHO is effective in sustaining reaction speed for a cognitive task but not promoting TT performance during hypoxic exercise, which would be important for strategy-/decision-making when athletes compete at moderate high-altitude.  相似文献   

超高含水原油混合流动及初始沉积特性     

邢晓凯  吕朝旭  刘珈铨 《中国科学院大学学报》2020,37(2):228-233

使用自行设计的实验装置，对超高含水原油的流动特性和初始沉积过程进行探究。系统研究实验温度、混合流速和体积含水率对超高含水原油初始沉积过程的影响，分析不同温度下原油的运动形态和初始沉积方式。初始沉积过程可分为蔓延沉积过程和粘连沉积过程，根据沉积特点和压降曲线的变化趋势将初始沉积过程分为3个阶段：沉积诱导期、快速沉积期和沉积动态平衡期。通过对沉积物碳数分布的分析，得知超高含水原油初始沉积过程中，同时存在剪切剥离作用、胶凝作用和分子扩散作用。实验温度和体积含水率主要通过改变胶凝作用和分子扩散来影响初始沉积过程，混合流速通过改变剪切剥离强度来影响初始沉积过程。  相似文献   

基于短时交通流量预测对路网微观交通仿真的研究     

张虎 《苏州市职业大学学报》2021,(1)

针对早高峰短时交通流量预测数据少、波动大的特点,提出用灰色模型进行预测。将灰色GM(2,1)改进为灰色GM(2,1,λ,ρ)预测模型,以提高预测精度。针对粒子群算法(PSO)的早熟现象,将Logistic混沌搜索嵌入到PSO算法,应用混沌粒子群算法(CPSO)寻找灰色GM(2,1,λ,ρ)预测模型最优的参数λ和ρ。结合两者提出了基于CPSO–GM(2,1,λ,ρ)的早高峰短时交通流预测模型。利用VISSIM对研究路网进行微观交通仿真,通过VISSIM–Excel、VBA–Matlab平台实现了短时交通流量预测和路网微观交通仿真数据的交互,对集成交通控制系统的架构进行了方案设计。仿真结果表明,结合流量预测的路网优于固定信号配时下的路网仿真。  相似文献   

CFD技术在无环量圆柱绕流多媒体教学中的应用研究     

李国威  董金玲 《中国现代教育装备》2011,(7):64-67

CFD技术是当前高等院校多媒体教学的热门手段和方法,特别是在如流体力学这样概念抽象,理论性强,与实际流动现象结合紧密的课程中显得尤为突出。文章应用Gambit,Fluent和Tecplot等相关软件,对无环量圆柱绕流的流动机理进行数值模拟与分析。目的在于验证无环量圆柱绕流数学、物理理论的正确性,观察流动现象,分析产生各种现象的原因。通过研究表明,以直观演示和定量分析相结合的方法,能够非常好地解决许多教学中的难点和重点问题,使学生对抽象的教学内容产生深刻的印象,增强了学习兴趣。  相似文献   

共享信息平台安全性研究     

陈珊  林智华 《福建工程学院学报》2008,6(1):58-61

共享信息平台的建立促进企事业网上业务的发展,但是平台的安全性问题日益严重.文章分析了信息平台建设存在的几个问题.认为应该从整个网络安全体系框架结构的设计出发,建立安全技术保障体系.可采用单点登陆、PKI认证、授权、基于角色的权限分配策略、利用应用网关访问资源,开发适合本系统的工作流访问机制等措施确保信息平台的安全.  相似文献