Simulation of Fragment Impact on Multi-Layer Targets Using Contact Method     

CRAWFORD John E 《天津大学学报(英文版)》2006,12(Z1)

Cased explosives generate highly energetic fragments as their casing breaks up. Due to the complexity of casing fragment related behavior such as embedment, perforation and ricochet, it may be insufficient to use equivalent triangular pressure loading in fragment impact simulations. This simplified method may over- or under-predict the target response. Recently, a procedure using contact techniques has been proposed to overcome such difficulties. It has been shown that the new method has the inherent capability in modeling the multi-piece and multi-hit fragment impact problems in a more realistic way. To investigate the applicability of the proposed method to simulations involving multi-layer penetration, the selected problems of fragment impact on multi-layer targets are described in this paper. It is demonstrated that this method is capable of predicting the complicated multi-layer structural response caused by fragment impact and penetration. Modeling procedures and some technical issues are also discussed.  相似文献   

Progress,trends, and practices in higher education: Lessons learned from a decade of assessment     

John A. Muffo 《Assessment Update》1996,8(5):1-11

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Special educational needs in mainstream secondary school physical education: learning support assistants have their say     

Anthony John Maher 《Sport, Education and Society》2016,21(2):262-278

Learning support assistants (LSAs) gained more political and academic attention in Britain after Estelle Morris announced that schools of the future would include more trained staff to support learning to higher standards. LSAs, thus, should form an integral part of the culture of all school departments in Britain, including physical education (PE). The paper uses Antonio Gramsci's concept of hegemony to explore the processes and practices that shape the views and experiences of LSAs and ultimately the extent to which they facilitate an inclusive culture in PE. A web survey gathered the views and experiences of LSAs vis-à-vis the inclusion of pupils with special educational needs (SEN) in mainstream secondary school PE in North-West England. A modified version of the tailored design method participant contact strategy resulted in 343 LSAs starting the web survey, with 154 (45%) following it through to completion. All quantitative data were analysed using Microsoft Excel whilst qualitative data were subjected to thematic analysis. This entailed the identification of recurring themes and patterns present in the data. The findings highlight the hegemonic status of English, maths and science when it comes to the allocation of SEN resources, which most LSAs support and often reinforce. PE is particularly disadvantaged in this hierarchy of subject priority. The majority of LSAs have not received PE-specific training, which brings into question their ability to facilitate inclusion in PE. Moreover, many schools do not appear to value the involvement of LSAs in the planning of differentiated lessons, which could have a negative impact on the PE experiences of some pupils with SEN given that LSAs are perhaps most aware of the specific learning needs of the pupils they support.  相似文献   

Red or dead     

John Williams 《Soccer & Society》2016,17(1):168-170

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Community,identity and contested notions of place: a study of Haitian recreational soccer players in the Dominican Republic     

Nicholas Wise  John Harris 《Soccer & Society》2016,17(4):610-627

Soccer is a sport not commonly associated with the Dominican Republic given the positioning of baseball as the national game. Yet, for some migrant groups in the country, such as those from Haiti, soccer plays an important part in their lives. Haitians have used soccer as a way to unite their communities and establish a sense of place. This paper assesses how these Haitian migrants use the game as a means of creating a community and developing a common focal point. Through participant observations and semi-structured interviews, this work may help us construct new understandings of the ways in which migrants use sport to assimilate to new surroundings and retain links to home.  相似文献   

Alterations in autonomic cardiac modulation in response to normobaric hypoxia     

David Giles  John Kelly 《European Journal of Sport Science》2016,16(8):1023-1031

Purpose: The present study aimed to determine if autonomic cardiac modulation was influenced by acute exposure to normobaric hypoxia. Method: Ten healthy male lowland dwellers completed five block-randomised single-blinded, crossed-over acute exposures to a normobaric hypoxic environment, each separated by 24 hours’ recovery (20.3%, 17.4%, 14.5%, 12.0% and 9.8% F_IO₂). Supine recordings were made of arterial oxygen saturation and electrocardiogram (ECG). RR intervals from the ECG trace were analysed for time (SDNN, lnrMSSD), frequency (lnVLF, lnLF, lnHF, lnTP, LFnu, and HFnu), and nonlinear (DFA-α1 and SampEn) heart rate variability components. Results: A significant reduction in arterial SaO₂ occurred with reduced F_IO₂, along with a rise in heart rate (Cohen’s d?=?1.16, 95% Confidence Interval [2.64–6.46]), significant at 9.8% F_IO₂. A decrease in autonomic cardiac modulation was also found as shown by a statistically significant (at 9.8% F_IO₂) decrease in lnTP (d?=?1.84 [1.74–1.94]), and SampEn (d?=?0.98 [0.83–1.12]) and an increase in DFA-α₁ (d?=?0.72 [0.60–0.84]) from normoxia at 9.8% F_IO₂. Conclusion: The decrease in variability indicated a reduction in autonomic cardiac modulation. There appears to be a threshold ～9.8% F_IO₂ (～6000?m equiv.), below which significant alterations in autonomic control occur.  相似文献   

Optical engineering for children – a structured approach     

John McCarthy  R. A. Moore 《European Journal of Engineering Education》2006,31(6):741-746

The present paper focuses on the application of a structured template, maximum impact flow (MIF), in order to encourage young students in the area of optics and optical engineering. MIF introduces a template in terms of individual steps and linked functionality and is shown to fuse separate learning tools together into a cohesive unit. Prioritization and teaching structures are also discussed with the promotion of technology identified as a key factor.  相似文献   

Defining the nature of blended learning through its depiction in current research     

Karen Smith  John Hill 《高等教育研究与发展》2019,38(2):383-397

ABSTRACT

Blended learning has been a feature of higher education practice and research for almost two decades. This article takes stock of current blended learning research, contributing to the growing number of meta-analyses of higher education and blended learning research more generally, through a review of ninety-seven articles relating to blended learning in higher education published in fifteen journals between 2012 and mid-2017. The review focused on where and when the articles were published; their provenance, scale, scope; methodological approach; the broad research themes; and definition of blended learning used. The review shows that despite its ubiquity, blended learning’s definition is all-encompassing; its spread is global but research is dominated by key players; it is of technical interest; and its research is small-scale, individually focused, seeking to evidence the benefits of blended learning. The article concludes with recommendations of how higher education research could provide institutions with evidence to ensure their ‘best of blends’.  相似文献   

Digital multimedia perception and design – Gheorghita Ghinea & Sherry Chen     

John G Hedberg   《British journal of educational technology : journal of the Council for Educational Technology》2007,38(1):173-173

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Special education and general education preservice teachers’ co-teaching experiences: a comparative synthesis of qualitative research     

Mikyung Shin  Hyunjoo Lee  John William McKenna 《International Journal of Inclusive Education》2016,20(1):91-107

Co-teaching is commonly used to support students with disabilities in inclusive educational settings. However, there is often a gap between the potential effectiveness of co-teaching and actual classroom practice. This study examined preservice teachers’ co-teaching experiences to better understand this gap to identify potential practices for improving teacher training and service delivery. A review of 11 studies revealed that both special education and general education preservice teachers believed that co-teaching practices provided them opportunities to communicate and work collaboratively. Both groups agreed on the significant impact of personality in co-teaching as well as challenges in implementing co-teaching. Furthermore, special education preservice teachers noted that they lacked content knowledge, whereas general education preservice teachers thought they needed more training in the provision of accommodations and modifications. Study limitations, areas for future research, and implications for preservice teacher preparation are discussed.  相似文献