This paper examines transformational learning experiences of computing students as a way to better understand threshold concepts in computing. From empirical evidence we found that students often describe transformati...
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ISBN:
(纸本)9781605582160
This paper examines transformational learning experiences of computing students as a way to better understand threshold concepts in computing. From empirical evidence we found that students often describe transformative experiences as learning situations in which they were led to use various kinds of abstraction, for example modularity, data abstraction, inheritance, polymorphism, reuse, design patterns, and complexity. Some students describe an abstract concept as coming first, and then needing to be made concrete though application;others describe transformations in which they learn the advantages of these abstract concepts from their experience of not using them. Abstraction is certainly of central importance in computer science. It appears, however, from our students' descriptions of transformative experiences, that abstraction per se is not a threshold, but that particular concepts in which abstraction is paramount exhibit the characteristics of threshold concepts. Copyright 2008 ACM.
A multi-marker automaton is a finite automaton which keeps marks as pebbles in the finite control, and cannot rewrite any input symbols but can make marks on its input with the restriction that only a bounded number o...
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As the number of components in cluster-based systems increases, costand power consumption also increase. One way to reduce both problems is usingsmaller networks with adequate congestion management mechanisms. Recents...
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ISBN:
(纸本)9783540898931
As the number of components in cluster-based systems increases, costand power consumption also increase. One way to reduce both problems is usingsmaller networks with adequate congestion management mechanisms. Recentsuccessful proposals (RECN) eliminate the negative effects of congestion,the Head-of-Line (HOL) blocking, leaving congestion harmless. RECN relies onsource-based networks architectures, where the entire route is placed at packetheaders before injection. Unfortunately, distributed table-based routing is alsocommon in cluster-based networks, being InfiniBand the most prominent *** propose a novel congestion management technique for distributed tablebasedrouting. The mechanism relies on additional congestion information locatedat routing tables. With this information HOL blocking is minimized bysmartly using switch queues. Detailed memory organization and the way congestioninformation is updated/propagated is described. Preliminary results indicatethat with modest resource requirements maximum network performance is keptregardless of congestion.
This paper presents a new logic style, named Current-Mode Differential logic (CMDL), that achieves both high operating speed and low power consumption. Inspired by the low-voltage swing (LVS) logic, CMDL uses a shunt ...
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In the realm of substation automation (SA), communication infrastructure plays a vital role in mediating between physical and virtual worlds of substation. Specification of data exchanges through standardized communic...
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In the realm of substation automation (SA), communication infrastructure plays a vital role in mediating between physical and virtual worlds of substation. Specification of data exchanges through standardized communication stacks is therefore an important issue for all substation equipment manufacturers seeking to provide vendor interoperability. Nowadays competitive electric utility marketplace, reliable and real-time information become the key factor for reliable delivery of power to the end- users, profitability of the electric utility and customer satisfaction. The operational and commercial demands of electric utilities require a high-performance data communication network that supports both existing functionalities and future operational requirements. As communication arena is changing day by day, the need for efficient and reliable communication infrastructure to address SA is evident. In this respect, a communication network constitutes the core of the SA, thus the design of cost-effective and reliable network architecture is a crucial task. Most of the existing communication networks claim to address the need of communication architecture for SA but in some regard these claims just could not fulfill the constraints imposed by highly available environment for SA. This paper presents a survey and analysis of the current state-of-the-art communication infrastructure in the SA. As Ethernet technology becomes more reliable and also widely available with fiber optical communication so this paper also examines the key issues and requirements for Ethernet in the substation environment and also opens some research challenges.
Digital broadcasting as new generation broadcasting offers a new opportunity for interactive services. For variety services of broadcasting, the broadcasting metadata becomes increasingly important and one of the meta...
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作者:
Hauschild, MarkSastry, KumaraPelikan, MartinGoldberg, David E.
Dept. of Mathematics and Computer Science University of Missouri St. Louis United States
Department of Industrial and Enterprise Systems Engineering University of Illinois Urbana-Champaign United States
University of Illinois Urbana-Champaign United States
Estimation of distribution algorithms (EDAs) are stochastic optimization techniques that explore the space of potential solutions by building and sampling probabilistic models of promising candidate solutions. While t...
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ISBN:
(纸本)9781605581309
Estimation of distribution algorithms (EDAs) are stochastic optimization techniques that explore the space of potential solutions by building and sampling probabilistic models of promising candidate solutions. While the primary goal of applying EDAs is to discover the global optimum (or an accurate approximation), any EDA also provides us with a sequence of probabilistic models, which hold a great deal of information about the problem. Although using problem-specific knowledge has been shown to significantly improve performance of EDAs and other evolutionary algorithms, this readily available source of information has been largely ignored by the EDA community. This paper takes the first step towards the use of probabilistic models obtained by EDAs to speed up the solution of similar problems in the future. More specifically, we propose two approaches to biasing model building in the hierarchical Bayesian optimization algorithm (hBOA) based on knowledge automatically learned from previous runs on similar problems. We show that the methods lead to substantial speedups and argue that they should work well in other applications that require solving a large number of problems with similar structure. Copyright 2008 ACM.
作者:
Pelikan, MartinSastry, KumaraGoldberg, David E.
Dept. of Mathematics and Computer Science 320 CCB Univ. of Missouri in St. Louis One University Blvd. St. Louis MO 63121 United States
Dept. of Industrial and Enterprise Systems Engineering Univ. of Illinois at Urbana-Champaign Urbana IL 61801 United States
This paper proposes the incremental Bayesian optimization algorithm (iBOA), which modifies standard BOA by removing the population of solutions and using incremental updates of the Bayesian network. iBOA is shown to b...
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ISBN:
(纸本)9781605581309
This paper proposes the incremental Bayesian optimization algorithm (iBOA), which modifies standard BOA by removing the population of solutions and using incremental updates of the Bayesian network. iBOA is shown to be able to learn and exploit unrestricted Bayesian networks using incremental techniques for updating both the structure as well as the parameters of the probabilistic model. This represents an important step toward the design of competent incremental estimation of distribution algorithms that can solve difficult nearly decomposable problems scalably and reliably. Copyright 2008 ACM.
In this paper we discuss experimental results obtained with a prototype implementation of an agent-based service for generic auctions that is currently under development. We configured the service to allow parallel ex...
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In this paper we discuss experimental results obtained with a prototype implementation of an agent-based service for generic auctions that is currently under development. We configured the service to allow parallel execution of multiple English auctions with buyer and seller agents bidding from different machines. The experimental results to assess the performance of the service include latency and throughput of the service as functions of the number of participants and the number of simultaneously active auctions.
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