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1.
In the classical multiprocessor scheduling problems, it is assumed that the problems are considered in off-line or on-line
environment. But in practice, problems are often not really off-line or on-line but somehow in between. This means that, with
respect to the on-line problem, some further information about the tasks is available, which allows the improvement of the
performance of the best possible algorithms. Problems of this class are called semi on-line ones. The authors studied two
semi on-line multiprocessor scheduling problems, in which, the total processing time of all tasks is known in advance, or
all processing times lie in a given interval. They proposed approximation algorithms for minimizing the makespan and analyzed
their performance guarantee. The algorithms improve the known results for 3 or more processor cases in the literature.
Project supported by the National Natural Science Foundation of China (Nos. 19701028 and 19971078) and National 973 Research
Project of China. 相似文献
2.
Parallel machine scheduling problems, which are important discrete optimization problems, may occur in many applications.
For example, load balancing in network communication channel assignment, parallel processing in large-size computing, task
arrangement in flexible manufacturing systems, etc., are multiprocessor scheduling problem. In the traditional parallel machine
scheduling problems, it is assumed that the problems are considered in offline or online environment. But in practice, problems
are often not really offline or online but somehow in-between. This means that, with respect to the online problem, some further
information about the tasks is available, which allows the improvement of the performance of the best possible algorithms.
Problems of this class are called semi-online ones. In this paper, the semi-online problemP2|decr|l
p (p>1) is considered where jobs come in non-increasing order of their processing times and the objective is to minimize the sum
of thel
p norm of every machine's load. It is shown thatLS algorithm is optimal for anyl
p norm, which extends the results known in the literature. Furthermore, randomized lower bounds for the problemsP2|online|l
p andP2|decr|l
p are presented.
Project supported by the National Natural Science Foundation of China (Nos. 10271110, 10301028) and the Teaching and Research
Award Program for Outstanding Young Teachers in Higher Education Institutions of MOE, China 相似文献
3.
In this study we investigate a strategy for engaging high school mathematics teachers in an initial examination of their teaching in a way that is non-threatening and at the same time effectively supports the development
of teachers’ pedagogical content knowledge [Shulman (1986). Educational Researcher, 15(2), 4–14]. Based on the work undertaken by the QUASAR project with middle school mathematics teachers, we engaged a group
of seven high school mathematics teachers in learning about the Levels of Cognitive Demand, a set of criteria that can be
used to examine mathematical tasks critically. Using qualitative methods of data collection and analysis, we sought to understand
how focusing the teachers on critically examining mathematical tasks influenced their thinking about the nature of mathematical
tasks as well as their choice of tasks to use in their classrooms. Our research indicates that the teachers showed growth
in the ways that they consider tasks, and that some of the teachers changed their patterns of task choice. Further, this study
provides a new research instrument for measuring teachers’ growth in pedagogical content knowledge.
An earlier version of this paper was presented at the American Educational Research Association Annual Meeting, New Orleans,
LA, April 2002. 相似文献
4.
Parallel machine scheduling problems, which are important discrete optimization problems, may occur in many applications. For example, load balancing in network communication channel assignment, parallel processing in large-size computing, task arrangement in flexible manufacturing systems, etc., are multiprocessor scheduling problem. In the traditional parallel machine scheduling problems, it is assumed that the problems are considered in offline or online environment. But in practice, problems are often not really offline or online but somehow in-between. This means that, with respect to the online problem, some further information about the tasks is available, which allows the improvement of the performance of the best possible algorithms. Problems of this class are called semi-online ones. In this paper, the semi-online problem P2|decr|lp (p＞1) is considered where jobs come in non-increasing order of their processing times and the objective is to minimize the sum of the lp norm of every machine's load. It is shown that LS algorithm is optimal for any lp norm, which extends the results known in the literature. Furthermore, randomized lower bounds for the problems P2|online|lp and P2|decr|lp are presented. 相似文献
5.
孔晓红 《河南科技学院学报》2007,35(2):46-49
目前大规模的并行分布多处理机系统中,调度算法好坏直接影响计算系统的高性能计算潜力能否发挥,调度的目的就是如何分配资源使系统性能最优。本文主要讨论分布式多处理机系统进行任务调度时的关键问题,包括问题模型的描述,调度策略,常用算法,评估标准,数据平台以及该问题的发展趋势。 相似文献
6.
HU Xin ZHANG Pu HE Sailing 《浙江大学学报(A卷英文版)》2006,7(10):1777-1780
A dual structure of composite right/left handed （CRLH） transmission line （TL） is analyzed in which an inductance LR is in parallel with a capacitance CL and a shunt capacitance CR is in series with an inductance LL. Both the distributed and lumped cases are considered. The dispersion diagram and transmission properties of the dual CRLH TL are given and compared with those of a standard CRLH TL. Contrary to the frequency response of a standard CRLH TL, a dual CRLH TL has a left-handed （negative phase shift） band at higher frequencies and a right-handed （positive phase shift） band at lower frequencies. A novel dual-band balun is presented as an application. 相似文献
7.
考虑变时间分数阶扩散方程。首先利用分段线性插值法结合对一阶时间导数的一个二阶近似离散Coimbra变时间分数阶导数,然后利用Richardson外推法改进精度,最后用数值例子来验证提出的数值方法,从而说明数值方法的有效性。 相似文献
8.
The evolvable multiprocessor （EvoMP）, as a novel multiprocessor system-on-chip （MPSoC） machine with evolvable task decomposition and scheduling, claims a major feature of low-cost and efficient fault tolerance. Non-centralized control and adaptive distribution of the program among the available processors are two major capabilities of this platform, which remarkably help to achieve an efficient fault tolerance scheme. This letter presents the operational as well as architectural details of this fault tolerance scheme. In this method, when a processor becomes faulty, it will be eliminated of contribution in program execution in remaining run-time. This method also utilizes dynamic rescheduling capability of the system to achieve the maximum possible efficiency after processor reduction. The results confirm the efficiency and remarkable advantages of the proposed approach over common redundancy based techniques in similar systems. 相似文献
9.
A follow‐up study was conducted on AS, previously reported as an English‐Japanese bilingual with monolingual phonological dyslexia in English ( Wydell and Butterworth, 1999 ). It was hypothesised that AS's fundamental deficit which lead to his dyslexia in English would still persist despite him successfully taking a BSc course in an English‐speaking country. AS and his Japanese and English control participants were asked to read aloud a target stimulus first, and then to decide whether the target was a word or nonword. Unlike the control participants, AS showed a marked dissociation between his performance in the lexical (orthographic and phonological) decision and the word naming tasks. Often those words and pseudo‐homophones (e.g. neym), which AS read erroneously, were correct in the decision tasks – the target pseudo‐homophone or word was substituted by another orthographically similar word. The results thus demonstrated that his reading of unfamiliar words or nonwords is essentially based on orthographic approximation using the visual similarities between words. The results confirmed the earlier finding that AS has a core phonological deficit which led to his dyslexia but never affected his reading in Japanese. The results also confirmed that this deficit persists when reading in English. This implies that whatever the neurological abnormality that AS may have, this only affects certain languages, and this abnormality persists with time. 相似文献
10.
本文基于Petri网模型,研究并行系统分叉和交汇操作过程的控制问题。通过把系统所要满足的性能要求转化为同一组线性不等式约束表示的控制问题,给出了综合这一类并行系统分叉和交汇操作过程Petri网控制器的方法。 相似文献
11.
Sheri Madigan Andre Plamondon Dillon Browne Jennifer Jenkins 《Parenting, science and practice》2016,16(2):108-124
Objective. To further understanding of the stability and variability in maternal behavior across tasks, time, and sibling pairs. Design. Mothers (a total of 451) were observed separately in interactions with two of their children across two tasks and three time points. Independent observers rated responsive and negative maternal behaviors. Results. Moderate to large correlations across tasks (responsivity = .51; negativity = .41), time points (responsivity = .40; negativity = .38), and siblings (responsivity = .56; negativity = .49) were found. Although these correlations indicate significant stability (i.e., consistency) of maternal behavior, they also indicate variability, with unexplained variance ranging from 69–84% for responsivity and 75–86% for negativity. Conclusions. Proportions of maternal behavior across tasks, time, and siblings can and cannot be accurately predicted given examination of maternal behavior in a comparable task, later time point, or sibling. The current study underscores the importance of considering both stability and variability as equally critical components for understanding maternal behavior. 相似文献
12.
Evelyn S. Chiang David J. Therriault Bridget A. Franks 《Metacognition and Learning》2010,5(2):121-135
In recent decades, increasing numbers of studies have focused on metacomprehension accuracy, or readers’ ability to distinguish
between texts comprehended more vs. less well. Following early findings that suggested readers are fairly poor at doing so,
a number of studies have identified specific tasks to supplement a single reading of text that have resulted in greater metacomprehension
accuracy. One assumption underlying these studies is that, in the absence of such tasks, metacomprehension accuracy is uniformly
poor, and given their implementation, readers uniformly improve. Here we describe the individual variation that occurs both
in the absence (e.g., within a single text reading manipulation) and presence (e.g., within a rereading or selective rereading task manipulation) of these supplementary tasks (N = 214), in order to make a case for greater attention to individual differences in metacomprehension accuracy. We also introduce
a new manipulation in metacomprehension research, selective rereading, and argue that certain types of tasks may be more likely
to reveal individual differences in metacomprehension accuracy due to the nature of the task being more or less demanding
on working memory capacity. 相似文献
13.
Andrew Chang Yao-Chuen Li Jennifer F. Chan Dobromir G. Dotov John Cairney Laurel J. Trainor 《Child development》2021,92(5):e907-e923
Accurate time perception is crucial for hearing (speech, music) and action (walking, catching). Motor brain regions are recruited during auditory time perception. Therefore, the hypothesis was tested that children (age 6–7) at risk for developmental coordination disorder (rDCD), a neurodevelopmental disorder involving motor difficulties, would show nonmotor auditory time perception deficits. Psychophysical tasks confirmed that children with rDCD have poorer duration and rhythm perception than typically developing children (N = 47, d = 0.95–1.01). Electroencephalography showed delayed mismatch negativity or P3a event-related potential latency in response to duration or rhythm deviants, reflecting inefficient brain processing (N = 54, d = 0.71–0.95). These findings are among the first to characterize perceptual timing deficits in DCD, suggesting important theoretical and clinical implications. 相似文献
14.
JULIA KWONG 《Chinese Education & Society》2013,46(5):3-6
This issue and the next deal with aspects of the examination system in China, in particular the gaokao (college and university entrance examination) and huikao (upper middle school general graduation examinations). The aim is to provide background information regarding policies, recent reforms, opinions, suggestions, and criticisms. While most attention is focused on the changes in the period since 1988, brief references are also made to reforms since 1949 and even earlier periods, including the keju (imperial examination system). Aside from such contextual references, occasional comparisons are also made with American and other Western examination systems. 相似文献
15.
多处理机系统Cache共享数据乒乓效应的研究 总被引：4，自引：1，他引：4
分析了多处理器系统中高速缓存共享数据乒乓效应的产生原因,并提出使用硬件和软件等方法处理多处理机系统的Cache中共享数据乒乓效应的几种对策。 相似文献
16.
Gradual refinement for application-specific MPSoC design from Simulink model to RTL implementation 总被引：1，自引：0，他引：1
Kai Huang Xiao-lang Yan Sang-il Han Soo-ik Chae Ahmed A. Jerraya Katalin Popovici Xavier Guerin Lisane Brisolara Luigi Carro 《浙江大学学报(A卷英文版)》2009,10(2):151-164
The application-specific multiprocessor system-on-chip （MPSoC） architecture is becoming an attractive solution to deal with increasingly complex embedded applications, which require both high performance and flexible programmability. As an effective method for MPSoC development, we present a gradual refinement flow starting from a high-level Simulink model to a synthesizable and executable hardware and software specification. The proposed methodology consists of five different abstract levels： Simulink combined algorithm and architecture model （CAAM）, virtual architecture （VA）, transactional accurate architecture （TA）, virtual prototype （VP） and field-programmable gate array （FPGA） emulation. Experimental results of Motion-JPEG and H.264 show that the proposed gradual refinement flow can generate various MPSoC architectures from an original Simulink model, allowing processor, communication and tasks design space exploration. 相似文献
17.
The dual formulation of the discrete-time mixedl
2/l
1 control design problem was achieved by using the duality theory of Lagrange multipliers. For some special dual mixedl
2/l
1 problems, an approximation method for the optimal value is introduced. A suboptimal value of the infinite-dimensional dual
problem can be obtained by solving a sequence of truncated problems. The convergence property of the solution scheme is investigated.
This paper gives a low approximation method for the primal problem.
Project(699085) supported by Zhejiang Provincial Natural Science Foundation of China. 相似文献
18.
Changing the way children make their response appears to sometimes, but not always, boost their inhibitory control—though interpreting existing findings is hampered by inconsistent methods and results. This study investigated the effects of delaying, and changing, the means of responding. Ninety-six preschoolers (Mage 46 months) completed tasks assessing inhibitory control, counterfactual reasoning, strategic reasoning, and false belief understanding. Children responded either immediately or after a delay, and either by pointing with their finger, or with a hand-held arrow. Delaying boosted performance on all tasks except false belief understanding; arrow-pointing only improved strategic reasoning. It is suggested that delay helps children work out the correct response; it is unlikely to help on tasks where this requirement is absent. 相似文献
19.
Richard J. Shavelson Maria Araceli Ruiz-Primo Edward W. Wiley 《Journal of Educational Measurement》1999,36(1):61-71
In 1993, we reported in Journal of Educational Measurement that task-sampling variability was the Achilles' heel of science performance assessment. To reduce measurement error, tasks needed to be stratified before sampling, sampled in large number, or possibly both. However, Cronbach, Linn, Brennan, & Haertel (1997) pointed out that a task-sampling interpretation of a large person x task variance component might be incorrect. Task and occasion sampling are confounded because tasks are typically given on only a single occasion. The person x task source of measurement error is then confounded with the pt x occasion source. If pto variability accounts for a substantial part of the commonly observed pt interaction, stratifying tasks into homogenous subsets—a cost-effective way of addressing task sampling variability—might not increase accuracy. Stratification would not address the pro source of error. Another conclusion reported in JEM was that only direct observation (DO) and notebook (NB) methods of collecting performance assessment data were exchangeable; computer simulation, short-answer, and multiple-choice methods were not. However, if Cronbach et al. were right, our exchangeability conclusion might be incorrect. After re-examining and re-analyzing data, we found support for Conbach et al. We concluded that large task-sampling variability was due to both the person x task interaction and person x task x occasion interaction. Moreover, we found that direct observation, notebook and computer simulation methods were equally exchangeable, but their exchangeability was limited by the volatility of student performances across tasks and occasions. 相似文献
20.
杨种学 《南京晓庄学院学报》2005,21(5):65-70
发现关联规则是数据挖掘技术的重要任务之一。之前提出的绝大多数算法需要多次遍历数据库才能产生频繁项集,造成巨大的CPU和内存开销。根据网上交易数据海量的特点,提出了一种基于频繁模式增长(FP-growth)的并行算法。该算法可以在不产生候选集的基础上并行的挖掘海量数据。试验证明该算法可以缓解了项目数量巨大而内存不足的矛盾,减少了算法的执行时间。利用该算法对网上交易进行关联规则挖掘,发现了有价值的决策支持信息。 相似文献