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1.
A number of authors have proposed that preference for a larger, delayed reward in delay discounting is similar to cooperation
in a repeated prisoner's dilemma game versus tit-for-tat. This proposal was examined by correlating delay-discounting (Experiment
1) and probability-discounting (Experiment 2) rates for hypothetical monetary gains and losses with performance in a repeated
prisoner's dilemma game. Correlations between rate of delay discounting (discounting parameters and area under the curve)
and proportion of cooperation in the repeated prisoner's dilemma game versus tit-for-tat were significant across three magnitudes,
and correlations were generally higher with discounting for losses than with that for gains. As was expected, correlations
between rate of delay discounting and performance versus a random strategy in the prisoner's dilemma game were not significant.
Correlations between rate of probability-discounting and cooperation rate in a repeated prisoner's dilemma game versus neither
a tit-for-tat nor a random strategy were significant. 相似文献
2.
Totransmitthemultimediadataovertheinternet ,pre encodedvideobitstreamsarepreferablebecauseofthelimitofthenetworkbandwidth .Inmostcases ,theencodershouldknowthechannelcharacteristicsinad vanceandencodethemasparameters .Consequently ,theflexibilityisreduced .Theratecontrolisemployedtocontroltheoutputbitrateaccordingtonetworkcondi tions.Forwirelessnetworks ,theirbandwidthsaremuchmorelimitedthanwirenetworks.Soratecontrolbecomesespeciallyimportantfortransmittingmultimediaoverthewirelessdomains[1- … 相似文献
3.
The existing H.264/AVC rate control schemes rarely include the perceptual considerations. As a result, the improvements in visual quality are hardly comparable to those in peak signal-to-noise ratio （PSNR）. In this paper, we propose a perceptual importance analysis scheme to accurately abstract the spatial and temporal perceptual characteristics of video contents. Then we perform bit allocation at macroblock （MB） level by adopting a perceptual mode decision scheme, which adaptively updates the Lagrangian multiplier for mode decision according to the perceptual importance of each MB. Simulation results show that the proposed scheme can efficiently reduce bit rates without visual quality degradation. 相似文献
4.
公共应急事件衍生上的关联性和潜在性、后果上的扩散性和颠覆性,使得重构一种能够有效预防预控未来应急事件的治理机制成为迫切需要。预见式行动视角下的公共应急治理是一种以多主体深入嵌合为驱动力,以未来潜在的公共应急事件为目标朝向,包括预判断、预认知、预创策略及预应对等环节的轮状运作过程,表现出循环可逆性、未来面向性和自反性等特征。该机制以循环治理结构替代了线性治理结构、以全过程的行动合作代替了政府为主的断点式分层合作、以跨时空的未来面向规避了现实面向的滞后性、以多维多层的系统方法优化了单维平面认知的局限性,具有推动公共应急治理机制演进变迁的工具理性意义。其实践中面临的主体合作困境、组织困境、能力困境以及信息提取困境,需要从人类关系的重组、组织结构的再造、社会预见能力的培育以及应急技术手段的审慎运用等方面予以突破。 相似文献
5.
撒拉族农村地区的教育现状与困境 总被引：3，自引：0，他引：3
撒拉族农村地区人口中盲率高，儿童入学率低，轰学现象严重的状况是社会，学校，家庭等多方面客观条件和主观认识共同作用的结果。发现民族地区的教育事业，除了需要继续加大教育的经济投入以外，关注民族地区的社会发展现状与化特点，关注人们的实际需要，对于走出民族地区教育发展的困境同样重要。 相似文献
6.
本文提出一种用于无线ATM网络多媒体业务的CAC方案。在该方案中，延迟约束用于可变比特速率，抖动约束服务质量(QoS)用于不变比特速率，从而保证了所有通信预定义的服务质量要求。为了减少切换掉话率，CAC方案赋予切换呼叫的优先权比新呼叫的高，并预约适当资源用于潜在的切换呼叫。CAC方案中的资源预留是通过用户移动信息来确保资源有效利用。分析结果表明，所提出的CAC方案能取得较低的切换掉话率和较高的系统资源利用率。 相似文献
7.
“科学大众化”的困境：社会学的分析 总被引：2，自引：0，他引：2
科学大众化是当今科学教育的一个核心概念,但在教材和教学层面,科学大众化却面临困境。这种困境主要体现为科学素养内容的不均衡性,即过分重视学科内容而忽视相应的个人、社会和文化意义。文章从科学家的学术控制和学校文化两个角度分析了这种不均衡性的原因。文章最后从两种理科课程取向之间的张力出发,提出科学教育家可能是科学大众化走出困境的希望。 相似文献
8.
ZHU Xiao-liang YANG Zong-kai DU Xu CHENG Wen-qing 《浙江大学学报(A卷英文版)》2006,7(10):1702-1708
INTRODUCTION Video streaming applications generally require continuous high bandwidth guarantees as well as stringent bounds on delays and jitters (Shen et al., 2004; Hassan and Krunz, 2004). Providing video streaming with acceptable quality degradation over wireless channels is fraught with challenges due to the adverse influence of bandwidth limitation, time variation, high error rate, and so on (Etoh and Yo- shimura, 2005; Shen et al., 2004; Chen and Zakhor, 2004; Hassan and Krunz, … 相似文献
9.
R. Clarke Fowler 《Early Childhood Education Journal》2017,45(2):155-162
The field of early childhood education (ECE) is currently unable to reach consensus on the extent to which ECE should be based on child development. One manifestation of this situation is the dilemma that early educators purportedly face between teaching the whole child and the curriculum, between developmentally appropriate practice (DAP) and standards. The source of this dilemma is attributed to a one-dimensional understanding of children’s development in which development is privileged over learning. Addressing this dilemma begins by discussing a theoretical difference between Piaget and Vygotsky: for Piaget, development drives learning; for Vygotsky, learning drives development. This seemingly dichotomous difference is reframed, however, by the insight that Piaget and Vygotsky focused on different types of development: Piaget studied universals (e.g., object permanence); Vygotsky studied nonuniversals (e.g., cultural tools often learned in schools). Their dispute stems, therefore, from this factor: development drives learning in nonuniversal developmental sequences, but learning drives development in universal sequences. Teachers who adopt a multi-dimensional developmental framework—a framework that makes visible how the relationship between learning and development may vary within universal versus nonuniversal developmental sequences—may be better prepared to (1) make informed decisions about the extent to which they should guide children’s activities and (2) avoid the DAP versus standards dilemma. The most recent iteration of DAP moved toward adopting a multi-dimensional developmental framework when it encouraged teachers to base instructional judgments on the extent to which children’s emerging capacities will likely require greater versus lesser degrees of adult guidance, structure, and support. 相似文献
10.
Brahm Norwich 《British Educational Research Journal》2009,35(3):447-467
This article reports findings from an international study about dilemmas of difference in relation to special educational needs and disability in education. It was part of a larger study of the perspectives of 132 education practitioners and policy makers in England, the USA and the Netherlands to a range of dilemmas of difference. It also compares these current perspectives with ones from similar groups in England and the USA from the early 1990s. Participants were interviewed about their perspectives on a presented dilemma about the consequences of identifying children as having a disability or a special educational need. The data are presented in quantitative terms (degrees of recognition and resolution of dilemma) and qualitative terms (reasons, justifications and suggested resolutions). The findings show variations in responses to the dilemma that relate to national differences, but also commonalities in the recognition of this dilemma, reasons for recognising and ways of resolving the dilemma. 相似文献
11.
CHOU Philip A 《浙江大学学报(A卷英文版)》2006,7(5):737-748
INTRODUCTION Many applications, such as software distribution, Internet TV/video streaming, video conferencing, multiplayer gaming, personal media distribution and P2P web content duplication, distribute the same content from one source node to many destination nodes. For these applications, IP multicast is an ideal network layer solution. A distribution tree rooted at the source can be formed to reach an arbitrary number of receivers. During content distribution, every single piece of… 相似文献
12.
INTRODUCTION Video streaming service nowadays enjoys ex- plosive adoptions over all kinds of underlying net- works. To enjoy the freedom of tether-less connection over the wireless local area network (WLAN), we need to overcome many challenges of unstable wire- less channel due to fading, interference and so on. The scarce and fluctuating available bandwidth (together with time-varying delays and random/burst losses) can cause the video quality at the streaming client to be seriously deg… 相似文献
13.
Brahm Norwich 《欧洲特需教育杂志》2013,28(4):287-304
This paper reports findings about placement questions relevant to disability in education. It is part of a larger international study of the perspectives of 132 education practitioners and administrators in England, the USA and The Netherlands to several dilemmas of difference. Participants were interviewed about their perspectives to a presented placement dilemma about the consequences of having inclusive/separate placements for children with more severe disabilities/special educational needs. The data are presented in quantitative terms (degrees of recognition and resolution of dilemma) and qualitative terms (reasons, justifications and suggested resolutions). The findings show the continued recognition of this dilemma and commonalities in the resolution of the dilemma across the countries. Variations in responses to the dilemmas that relate to national differences are also discussed. 相似文献
14.
异步电机按定子磁链定向的转矩连续控制 总被引：5，自引：0，他引：5
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15.
Frame skipping in low bit video coding could significantly reduce the visual quality of reconstructed video. At the same time, if the complexity of the video sequence remains high for a long period, then driving up the long term average bit rate, the only resort of MPEG-4 Q2 rate control algorithm results in using a high quantization scale, which shows a poor visual quality of the reconstructed video. This paper analyzes the main causes of frame skipping in current MPEG-4 frame rate control scheme, and presents a new rate control algorithm based on the quadratic R-D model over a CBR channel. Key features of the present work are. 1) the bits allocated to each P-frame or B-frame are in proportion to its distance from the end of this GOP, i.e. more bits are allocated to the frames that are nearer to their reference Ⅰ -frame: 2) the target buffer level is changeable in the GOP, at the end of each GOP( five P-frames or B-frames), the target buffer level is linearly reduced from 1/2 to 1/4 of buffer size, to other frames, the target buffer level is set to 1/2 of buffer size: 3 ) a selective and judicious use of the reduced resolution mode, in addition to a modulation of the quantization scale parameter, is to control the average long term bit rate. Experimental results with different video sequences of varied complexity, encoded at low bit rates show better efficacy of the proposed algorithm than MPEG-4 Q2 rate control scheme, and the experimental results also show that the improved algorithm has significantly reduced the number of frame skipping, increased the overall PSNR, and improved the perceptual quality. 相似文献
16.
Research on the counterintuitive Monty Hall dilemma (MHD) and analogous problems has shown that correct reasoning is rarely observed, even with the help of certain hints. Making the causal structure explicit or presenting probabilities by means of natural frequencies seem to enhance performance, but only to a moderate degree. The present experiments aimed to analyze the usefulness of these hints for solving an analogous MHD in more detail. Results showed that, compared to relative frequencies, natural frequencies improved reasoning, but this effect depended on previous numerical skills. On the other hand, a graph representing the causal structure had no effect, suggesting that numerical representations are more critical for solving the dilemma. Furthermore, success in solving the dilemma strongly correlated with participants’ skill in representing probabilities. Hence, an adequate numerical representation seems to be particularly relevant for understanding counterintuitive probabilistic problems. 相似文献
17.
In this work, we treat scattering objects, water, surface and bottom in a truly unified manner in a parallel finite-difference time-domain (FDTD) scheme, which is suitable for distributed parallel computing in a message passing interface(MPI) programming environment. The algorithm is implemented on a cluster-based high performance computer system.Parallel computation is performed with different division methods in 2D and 3D situations. Based on analysis of main factorsaffecting the speedup rate and parallel efficiency, data communication is reduced by selecting a suitable scheme of task division.A desirable scheme is recommended, giving a higher speedup rate and better efficiency. The results indicate that the unifiedparallel FDTD algorithm provides a solution to the numerical computation of acoustic scattering. 相似文献
18.
研究了移动Ad Hoc网络中的媒体接入控制问题. 首先, 基于IEEE 802. 11媒体接入控制协议, 提出了应用于MANET网络媒体接入控制的2个机制: 自适应回退窗转发优先机制(FPF)和多跳链邀请发送机制(MFCTI). FPF机制根据业务优先级自适应调整竞争窗大小, 而MFCTI机制则充分利用了网络层路由信息和无线传播的广播特性. 在此基础上对所提出的机制进行了仿真研究并与原IEEE 802. 11媒体接入控制进行了比较. 结果表明, 所提机制可以有效地提高网络吞吐率, 降低端对端迟延, 缓解网络局部拥塞, 从而提高了MANET网络的性能. 其另一优点是只需对IEEE 802. 11媒体接入控制作少量的补充和改动. 相似文献
19.
黄才华 《河南师范大学学报(哲学社会科学版)》2006,33(6):70-73
部分承担社会责任的企业存在决策困境的状况,原因是决策中的各种不确定因素。从理论概念看,企业的社会责任并未形成广泛认可的通行的定义;从现实情况看,企业社会责任决策过程中的不确定因素可以从以下四个方面进行分析:关于企业社会责任存在认识误区,企业面临的决策环境是不确定的,决策者素质存在差异,方案形成困难导致不确定性增加。如果处理不当,这些因素中的多个甚至一个也能导致承担社会责任的企业陷入决策困境。决策者应尽力减轻这些不确定性所带来的负面作用,以便做出有责任的判断和选择。 相似文献
20.
当前,市场经济在带来高效率、离增长的同时也带给人们严重的价值冲突和困境。因此。澄清这些价值冲突与困境的原因,合理调适市场经济与社会主义之间的关系是克服当前价值困境的有效途径。’ 相似文献