共查询到20条相似文献，搜索用时 359 毫秒
1.
Simulation of Airblast Load and Its Effect on RC Structures 总被引：1，自引：0，他引：1
In the analysis of a structure subjected to an explosion event, the determination of the blast load constitutes a crucial step. The effect of the blast load on the structure depends not only on the peak shock overpressure, but also the impulse (hence the duration). For structures with a regular geometry, the blast load may be fairly well estimated using appropriate empirical formulae; however, for more complex situations, a direct simulation using appropriate computational techniques is necessary. This paper presents a numerical simulation study on the prediction of the blast load in free air using a hydrocode, with focus on the sensitivity of the simulated blast load to the mesh grid size. The simulation results are compared with empirical predictions. It is found that the simulated blast load is sensitive to the mesh size, especially in the close-in range, and with a practically affordable mesh grid density, the blast load tends to be systematically underestimated. The study is extended to internal blast cases. An example concrete slab under internal explosion is analyzed using a coupled analysis scheme. The internal blast load from the simulation is examined and the response of the RC slab is commented. 相似文献
2.
The famous “six letters“ experiment carried out by Milgram demonstrated the existence of small-world effect in a complex network. One vertex tends to be connected to another by a shortest path through network because of the small-world effect. This paper uses the small-world effect to study protein folding pathway. 相似文献
3.
Over the last 20 years, science education studies have reported that there are very different understandings among students of science regarding the key aspects of climate change. We used the cognitive linguistic framework of experientialism to shed new light on this valuable pool of studies to identify the conceptual resources of understanding climate change. In our study, we interviewed 35 secondary school students on their understanding of the greenhouse effect and analysed the conceptions of climate scientists as drawn from textbooks and research reports. We analysed all data by metaphor analysis and qualitative content analysis to gain insight into students' and scientists' resources for understanding. In our analysis, we found that students and scientists refer to the same schemata to understand the greenhouse effect. We categorised their conceptions into three different principles the conceptions are based on: warming by more input, warming by less output, and warming by a new equilibrium. By interrelating students' and scientists' conceptions, we identified the students' learning demand: First, our students were afforded with experiences regarding the interactions of electromagnetic radiation and CO2. Second, our students reflected about the experience-based schemata they use as source domains for metaphorical understanding of the greenhouse effect. By uncovering the—mostly unconscious—deployed schemata, we gave students access to their source domains. We implemented these teaching guidelines in interventions and evaluated them in teaching experiments to develop evidence-based and theory-guided learning activities on the greenhouse effect. 相似文献
4.
CET-4 is held to assess whether the tasks assigned in the syllabus have been accomplished instead of being the baton conducting college English teaching. However, based on the structuralism testing theory, the present testing system has some unfavorable backwash effect on classroom teaching. In this article, an analysis of writing testing and writing teaching is put under close examination. And suggestions for its improvement such as a reform of writing teaching by taking writing as a process, emphasizing the development of thinking and its communicative function are proposed. 相似文献
5.
Sinem Aslan Nese Alyuz Eda Okur Sinem Emine Mete Ece Oktay Asli Arslan Esme 《Educational technology research and development : ETR & D》2018,66(6):1399-1413
The goal of this research is to investigate the effect of emotion-aware interventions on students’ behavioral and emotional states. To this end, we collected data from 12 students in the 9th grade in a high school in Turkey. The data collection took place in two sessions of an English Course. While the students were reading articles and solving relevant questions, our data collection application running in the background recorded the videos of the individual students through a camera and captured students’ screens in a non-intrusive manner. In total, we had 12.5 h of student data. We employed the human expert labeling process (HELP) (Aslan et al. in Workshop proceedings at international conference on intelligent tutoring systems (ITS), pp 156–165, 2016) to have the data labeled (150 h of data labeling in total). The data collection application was designed in a way that it also collected emotional self-labels (i.e., emotional states as self-reported by students at any time of learning). We leveraged emotional self-label information to suggest various real-time interventions for the students. The results obtained using the final expert labels showed that the percentage of the students’ Satisfied state was significantly higher after interventions. The results also demonstrated that although the interventions were triggered by the emotional states as self-labeled by the students and tailored to improve such states, there was a major positive impact of these interventions on students’ behavioral states. This preliminary study showed that even with a limited set of emotion-aware interventions based on self-labels, students’ states could be impacted positively. Conducting large-scale pilots leveraging more advanced interventions is a future direction for our research. 相似文献
6.
Affective factors play a positive role in English study and motivation is the most important.Higher motivation predicts better second language acquisition.The types of motivation are mainly divided into two:extrinsic motivation and intrinsic motivation.Teachers should study their students as well as the teaching materials and then select scientific methods and make good use of them to reinforce their students'motivation. 相似文献
7.
研究不同磺化度的磺化聚苯乙烯（ＳＰＳ）的荧光特性，ＳＰＳ的荧光光谱在２８５，３３５和３８０ｎｍ的发射峰分别对应于单体、激基缔合物及类激基缔合物的荧光发射．基态磺化苯乙烯基团形成的二聚体在光激发下产生类激基缔合物，类激基缔合物荧光随着ＳＰＳ磺化度的增加而增强．稀溶液中ＳＰＳ激基缔合物形的活化能和焓随着ＳＰＳ磺化度的增加而增大，且激基缔合物的稳定性增加 相似文献
8.
Carbonaceous mesophase derived from differentpitches has different features[1—4], such as sphere sizedistribution, deformability, and solubility. For themesophase used to produce fibers, homogeneous bulkmesophase is a desirable candidate[5,6]. Thus the o… 相似文献
9.
Nada Chatila Afra Iman Osta Wassim Zoubeir 《International Journal of Science and Mathematics Education》2009,7(1):103-132
This study attempted to investigate the alternative conceptions that a group of 12 Lebanese students in a grade 9 class hold
about electricity. It also attempted to evaluate learning outcomes of implementing in that class an inquiry-based module for
the acquisition of conceptual understanding of basic concepts in electricity. Fourteen mostly subjective tests were administered
throughout the implementation phase of the inquiry-based module to assess the evolution of participants’ conceptions. The
instrument DIRECT (Version 1.0) focusing on conceptual understanding was used as a post-instructional test to measure acquisition
of understanding. The findings revealed that most of the alternative conceptions reported in literature were found amongst
the participants. Results of the post-testing showed that the implemented inquiry-based approach was successful in enhancing
participants’ conceptual understanding of the targeted DC circuit concepts. 相似文献
10.
The effect of magnetic field on α-amylase was studied. Under the experimental conditions, α-amylase solution was treated by 0.15 T, 0.30 T and 0.45 T static magnetic fields for a known period of time, then the activ-ity, kinetic parameters, and the secondary conformation were investigated. The results showed that there was a con-siderable effect of the magnetic exposure on the α-amylase. The activity was increased by 27%, 34.1%, 37.8% compared with the control. It was also found that both kinetic parameters Km and Vm could be decreased due to the increasing magnetic field, Km decreased from 2.20×102 to 0.87×102, whereas Vm decreased from 2.0×103 g/min to 1.1×103g/min. At the same time, there were some irregular changes in α-amylase secondary conformation. 相似文献
11.
The effect of magnetic field on α-amylase was studied. Under the experimental conditions, α-amylase solution was treated by 0.15 T, 0.30 T and 0.45 T static magnetic fields for a known period of time, then the activity, kinetic parameters, and the secondary conformation were investigated. The results showed that there was a considerable effect of the magnetic exposure on the α-amylase. The activity was increased by 27%, 34.1%, 37.8% compared with the control. It was also found that both kinetic parameters K m and V m could be decreased due to the increasing magnetic field, K m decreased from 2.20×10?2 to 0.87×10?2, whereas V m decreased from 2.0×10?3 g/min to 1.1×10?3 g/min. At the same time, there were some irregular changes in α-amylase secondary conformation. 相似文献
12.
Sushanta Dattagupta 《Resonance》2018,23(9):949-963
In this article, we discuss how a combination of electrodynamics and quantum mechanics makes interference measurements of the quantum phase possible in terms of the vector potential, neither of which is detectable independently. This effect, predicted by Aharonov and Bohm, is of great significance in the contemporary interesting topic of nanoscopic physics. We also indicate how the effect can be incorporated in a solid state device by employing the tight-binding (TB) model. The TB model can be realized in a mesoscopic ring which allows the measurement of the bond current and the associated diamagnetism. An exactly solvable case of a threesite ring is presented that serves as a pedagogic example providing further insights into the phenomenon. 相似文献
13.
INTRODUCTION Polychlorinated biphenyls (PCBs) are members of the halogenated hydrocarbon class of lipophilic environmental endocrine disrupters that includes the dibenzofurans and dioxins. Their appearance in the ecosystem and in the tissues from wildlife, as well as documented cases of accidental poisoning led to the banning of their manufacture in 1977 (Tilson and Kodavanti, 1997). The PCBs continue to be of concern to biologists due to reports that exposure to relatively low levels… 相似文献
14.
李孝利的名字,从出道的第一天开始,就被冠上了"性感"的抬头。十年如一日。男人眼中的她,是性感女神。眼神、身材、气质,妖娆妩媚,是难以抵挡的诱惑。女人眼中的她,是羡慕又嫉妒对象。一件简单的 Tee,和一条最普通的牛仔裤,她都能把性感穿出极致。这个夏天,李孝利带着新专辑回归。专属于她的性感效应,正在火热蔓延…… 相似文献
15.
The present study aimed to investigate the effect of two major approaches of Dynamic Assessment, namely, interventionist and interactionist approaches, on learners’ oral narrative performance and anxiety. To this end, 34 Iranian EFL learners were assigned to an Interactionist Group (InA.G) and Interventionist Group (InV.G). Initially, both groups were given the Foreign Language Classroom Anxiety Scale and a pretest of speaking. In the treatment phase, the InV.G was asked to narrate a video and received instructions on their errors. The InA.G narrated the video while being provided with scaffolding during narration. Then both groups were given a posttest and, two weeks later, a delayed posttest. The results indicated that both groups’ oral performance significantly increased, while their anxiety reduced. In the end, a semi-structured interview was conducted whose results revealed that the InA.G experienced more anxiety mostly due to feeling a sense of interruption and losing face. 相似文献
16.
Before there were humans, the world changed only slowly. The climate warmed and cooled, new plants and animals developed and became extinct(绝灭的) in their turn, and sea level rose and fell over periods of thousands, if not millions of years. But during the last two thousand years great changes have taken place. 相似文献
17.
By tracing the history of instant messaging(IM),comparing the language used in English IM to historical English,and reviewing the current state of syntax and vocabulary used in IM,some predictions for the future of language can be made. 相似文献
18.
Before there were humans, the world changed only slowly. The climate warmed and cooled, new plants and animals developed and became extinct (绝灭的) in their turn, and sea level rose and fell over periods of thousands, if not millions of years. But during the last two thousand years great changes have taken place. Forests have disap- 相似文献
19.
Through a synthesis of test publisher norms and national longitudinal data sets, this study provides new national norms of academic growth in K–12 reading and math to help reinterpret conventional effect sizes in time units. We propose d?, a time-indexed–effect-size metric to estimate how long it would take for an “untreated” control group to reach the treatment group outcome in terms familiar to educators—years/months of schooling. It serves as a supplement to conventional effect-size metrics, such as Cohen's d, by taking into account different amounts of time needed for learning at different ages or grade levels. Through applications to Project STAR small class effects and NAEP racial achievement gaps, we demonstrate how to interpret and use d?. It is expected to provide a more developmentally appropriate context for interpreting the size of an effect, a step toward bridging the gap between educational research and practice. 相似文献
20.
徐巧燕 《读与写:教育教学刊》2013,(8):1-2
Jane Austin,a renowned British novelist,is a great master of language.She is skilled in depicting ironic,dramatic effect of narrative and dialogues.Pride and Prejudice is her masterpiece,whose unique artistic characteristics with dramatic effect attract generations of readers.To explore Austin’s dramatic effect and to further appreciate her amazing writing techniques,this paper conducts stylistic analyses of Pride and Prejudice.Firstly,Austin’s narrative techniques are explored stylistically from syntactic structure and schema refreshment perspective.Secondly,the dramatic dialogues between Bennet couple are analyzed from speech presentation and cooperative principles. 相似文献