基于STAR-CCM+的汽车挡风玻璃除霜性能提升的仿真分析与研究     

胡忠文 《苏州市职业大学学报》2021,(1)

采用计算流体动力学的方法,利用STAR-CCM+软件对某一车型挡风玻璃除霜性能进行数值模拟分析。通过对出风口格栅进行调整,改变了暖风气流与挡风玻璃之间碰撞角的大小与碰撞点的位置,优化了挡风玻璃表面暖风气流的分布,提升了除霜性能,为汽车除霜风道的设计和改善车辆除霜性能提供了参考。  相似文献   

Understanding the relative contribution of technical and tactical performance to match outcome in Australian Football     

Christopher M Young  Wei Luo  Paul B Gastin  Daniel B Dwyer 《Journal of sports sciences》2020,38(6):676-681

ABSTRACT

The aim of this study was to assess if tactical and technical performance indicators (PIs) could be used in combination to model match outcomes in Australian Football (AF). A database of 101 technical PIs and 14 tactical PIs from every match in the 2009–2016 Australian Football League (AFL) seasons was merged. Two outcome measures Win-loss and Score margin were used as dependent variables. The top 45 ranked technical and tactical PIs from a feature selection process were used to model match outcome using decision tree and Generalised Linear Models (GLMs). Of the top 45 selected features, this included seven tactical PIs. The Win-loss-based Decision tree model achieved a classification accuracy of 89.0% and GLM 93.2%. A Score margin-based GLM achieved a root mean squared error (RMSE) of 6.9 points. A combined approach to the classification of match outcomes provided no improvement in model accuracy compared with previous literature. However, this study has established the relative importance of technical and tactical measures of performance in relation to successful team performance in AF.  相似文献   

Outstanding performances during elite-standard short and middle-distance finals and the hyperandrogenism regulation—A detailed analysis of Caster Semenya’s results     

Jonathan Ospina-Betancurt  Maria S. Zakynthinaki 《Journal of sports sciences》2020,38(6):703-709

ABSTRACT

Recently, there has been much controversy over the International Association of Athletics Federation (IAAF) regulations regarding eligibility to compete and natural testosterone levels in female athletes. Much interest lies in the analysis of Caster Semenya's extraordinary performance. The objective of this work were, a) Complete an analysis of Caster Semenya's results during the 800m finals and b) search for existing similar performances by other female athletes. We analysed the results of the finals of all IAAF World Championships and Olympic Games from 1984–2016, including the 800m results of the Diamond Leagues 2016–2018. Exponential curves were fit to the data to characterise and predict performance for each event. Caster Semenya's finishing times before her ineligibility to compete and after the suspension of the IAAF hyperandrogenism regulation were found to be 1.24% and 1.49%, respectively, faster than the characteristic performance of the elite-standard in the women’s 800m final. Other female athletes, with finishing times faster than the ones predicted by the characteristic curves were also discovered. The percentage difference in performance between Caster Semenya and the other participants did not reach 3% in the 800m event. No conclusions can be drawn regarding extraordinary results ever performed during the 100m, 200m or 400m finals.  相似文献   

Real-time analytics,incident response process agility and enterprise cybersecurity performance: A contingent resource-based analysis     

《International Journal of Information Management》2021

Emerging paradigms of attack challenge enterprise cybersecurity with sophisticated custom-built tools, unpredictable patterns of exploitation, and an increasing ability to adapt to cyber defenses. As a result, organizations continue to experience incidents and suffer losses. The responsibility to respond to cybersecurity incidents lies with the incident response (IR) function. We argue that (1) organizations must develop ‘agility’ in their IR process to respond swiftly and efficiently to sophisticated and potent cyber threats, and (2) Real-time analytics (RTA) gives organizations a unique opportunity to drive their IR process in an agile manner by detecting cybersecurity incidents quickly and responding to them proactively. To better understand how organizations can use RTA to enable IR agility, we analyzed in-depth data from twenty expert interviews using a contingent resource-based view. The results informed a framework explaining how organizations enable agile characteristics (swiftness, flexibility, and innovation) in the IR process using the key features of the RTA capability (complex event processing, decision automation, and on-demand and continuous data analysis) to detect and respond to cybersecurity incidents as-they-occur which, in turn, improves their overall enterprise cybersecurity performance.  相似文献   

The impact of socioeconomic status on parental factors in promoting academic achievement in Chinese children     

《International Journal of Educational Development》2020

Children from families of low socioeconomic status (SES) tend to experience lower academic achievement than children from middle-SES families. This discrepancy can be attributed to a range of parental factors. The present study tested: (1) the extent to which academic achievement in three core subjects differs between children from low- and middle-SES backgrounds; (2) the differences in parental expectation, parental involvement, and child engagement across the two groups; and (3) the mediating role of parental expectation, parental involvement, and child engagement in explaining how SES influences children’s academic achievement. The sample consisted of 184 primary students with low SES and 165 primary students with middle SES from mainstream primary schools in Hong Kong. Results revealed significant differences in parental expectation, parental involvement, child engagement, as well as academic achievement in Chinese and English subjects between the low-SES and middle-SES groups. Our findings also suggest that parental expectation, parental involvement, and child engagement may be important mediators in the relationship between SES and academic achievement.  相似文献   

Towards a Framework for Evaluating the Research Performance of Chinese Double First-Class Universities     

XU Changqing 《Frontiers of Education in China》2020,15(3):369

The study focuses on the research performance of Double First-Class (DFC) universities in China. A theoretical framework based on economic theory and the Analytic Hierarchy Process (AHP) method for a novel evaluation model is proposed. The model is performed on a sample of 41 participant DFC universities in China. Using data collected from these universities, it was found that there is no consistency between performance ranking, input ranking, and output ranking, with the best ranked universities far from the most efficient. These findings provide empirical evidence of DFC universities’ research performance situation and suggest strategies that the government can use to propel their sustainable development.  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   

The effects of a calf pump device on second half performance of a simulated soccer match in competitive youth players     

S. Béliard  J. Cassirame  G. Ennequin  G. Coratella  N. Tordi 《Journal of sports sciences》2019,37(6):708-716

During soccer matches, performance decrements have been reported that relate to both physical abilities and technical skills. To investigate the effects of low-frequency electrical stimulation LFES (VeinoplusSport®, Ad Rem Technology, France) administered during half-time recovery on performance alterations during the second half. Twenty-two highly trained young players undertook a soccer-match simulation (SAFT⁹⁰). During half-time, they were randomly assigned to LFES group or Placebo group. Each half was split into 3 bouts of 12 minutes. Following each bout, maximal strike speed (MSS), sprint test (ST), maximal sprint accelerations (MA) and metabolic power (MP) were determined in both groups. Arterial (AF) and venous flows (VF) were measured at rest and at the end of half-time. LEFS group exhibited beneficial effects on performance compared to the Placebo group with a likely effect for MSS, ST, MA, and a possible effect for MP. AF and VF increased statistically more in LEFS group compared to Placebo group. The use of specific calf-pump LFES during half-time of a youth simulated soccer match attenuated the decrease in performance during the second half compared to Placebo group. This effect is most marked at the beginning of the second half with regards to explosive parameters.  相似文献   

The intermediating role of organizational culture and internal analytical knowledge between the capability of big data analytics and a firm’s performance     

《International Journal of Information Management》2020

Firms are increasingly relying on business insights obtained by deploying data analytics. Analytics-driven business decisions have thus taken a strategic imperative role for the competitive advantage of a firm to endure. The extent and effectiveness through which business firms can actually derive benefits by deploying big data-based practices requires deep analysis and calls for extensive research. This study extends the big data analytics capability (BDAC) model by examining the mediatory effects of organizational culture (CL) between internal analytical knowledge (KN) and BDAC, as well as the mediating effects of BDAC between CL and firm performance. The findings bring into focus that CL plays the role of complementary mediation between BDAC and KN to positively impact firm performance (FP); BDAC also plays a similar mediatory role between CL and the performance of a firm.  相似文献   

The context dependence of physics identity: Examining the role of performance/competence,recognition, interest,and sense of belonging for lower and upper female physics undergraduates     

Zahra Hazari  Deepa Chari  Geoff Potvin  Eric Brewe 《科学教学研究杂志》2020,57(10):1583-1607

While there is a growing body of work that examines disciplinary identity development, unlike qualitative work in this area, quantitative research has not fully incorporated the importance of different contexts, nor has it uniquely focused on underrepresented groups (in this case, women in physics). This study examines how the constructs posited by prior work as important for physics identity, as well as an additional theorized construct, may interrelate and affect female students' physics identity differently depending on the context. Context in this study refers to two different experiential levels in college. The constructs examined include performance/competence, recognition, and interest, as well as sense of belonging. In particular, we used structural equation modeling to examine the effect that these constructs have on the physics identity of two groups of female physics undergraduates: first year students and senior year students. The results reveal that the relationship of the theorized constructs with physics identity vary between the two groups as well as compared to prior research with broad college student populations (not just physics majors). Unlike broad college student populations, for our sample of female physics undergraduates, interest did not have a direct effect on physics identity while sense of belonging was significant only for senior year students. These results exemplify the importance of examining context or different types of student experiences when studying disciplinary identity development rather than generalizing previous frameworks to all contexts.  相似文献