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21.
Prosenjit Bose Paz Carmi Mirela Damian Robin Flatland Matthew J. Katz Anil Maheshwari 《Algorithmica》2014,69(2):397-409
For any angle α<2π, we show that any connected communication graph that is induced by a set P of n transceivers using omni-directional antennas of radius 1, can be replaced by a strongly connected communication graph, in which each transceiver in P is equipped with a directional antenna of angle α and radius r dir, for some constant r dir=r dir(α). Moreover, the new communication graph is a c-spanner of the original graph, for some constant c=c(α), with respect to number of hops. 相似文献
22.
Kevin P. Nolan Akshat Agarwal Shenghui Lei Robin Shields 《Microfluidics and nanofluidics》2016,20(7):101
Detailed measurements of the flow instability of dilute shear-thinning viscoelastic aqueous solutions, with relatively low zero-shear viscosities, in an obstructed microchannel flow are reported. We examine the flow behaviour resulting from a 100 μm post placed in the channel centreline over a range of Reynolds numbers (\(5<Re<300\)) and Weissenberg numbers (\(20<Wi<10^3\)). Micro-particle image velocimetry measurements show the onset of an upstream instability within a Reynolds number range and at a critical elasticity number corresponding to polymer concentrations above 25 ppm of long-chain polyacrylamide. The instability results in significant local fluctuations in the flow field approaching 30 % of the mean velocity. The magnitude of the local viscosity ratio in the region upstream of the post is proposed as a driving mechanism for the instability which resembles a buckling flow. Additionally, the classical instability owing to separation and vortex formation downstream of the post in Newtonian flow is suppressed and a very long stable wake is observed extending over 10 post-diameters downstream. 相似文献
23.
Faizal Riaz-ud-Din Robin Doss 《International Journal of Parallel, Emergent and Distributed Systems》2016,31(6):543-561
Database query verification schemes provide correctness guarantees for database queries. Typically such guarantees are required and advisable where queries are executed on untrusted servers. This need to verify query results, even though they may have been executed on one’s own database, is something new that has arisen with the advent of cloud services. The traditional model of hosting one’s own databases on one’s own servers did not require such verification because the hardware and software were both entirely within one’s control, and therefore fully trusted. However, with the economical and technological benefits of cloud services beckoning, many are now considering outsourcing both data and execution of database queries to the cloud, despite obvious risks. This survey paper provides an overview into the field of database query verification and explores the current state of the art in terms of query execution and correctness guarantees provided for query results. We also provide indications towards future work in the area. 相似文献
24.
25.
ABSTRACT Incorporating digital gaming into education is an increasingly popular topic in academia. Educators’ views of digital gaming (e.g., computer, video, and online games) have shifted from categorizing these games as an entertaining, yet pedagogically void activity to a promising medium that engages students in the learning process. With over 70% of college students enthusiastically playing digital games, educators are tapping into digital gaming as an effective means to teach millennials problem solving and communication skills. This article investigates gamer characteristics, motivational and engaging aspects of digital games, and the parallels between gaming and the information retrieval process. The authors build on this information to present approaches to incorporate digital gaming techniques into the library classroom since it is not feasible for all libraries to create instructional digital games. 相似文献
26.
Joshua Gorner Jie Zhang Robin Cohen 《Electronic Commerce Research and Applications》2013,12(2):112-123
This paper explores potential improvements to the trust modeling of agents in multi-agent systems when a social network of advisors is employed as part of the trust modeling, and in particular, examines means of optimizing the number of advisors that should be maintained in the social network. We propose three such improvements, two directly relating to the limit of advisor network size by either setting a maximum size for a buyer’s advisor network or setting a minimum trustworthiness threshold for agents to be accepted into that advisor network, and a third which uses an advisor referral system in combination with one of the first two network-limiting techniques. We provide experimental results in defence of our approach for two distinct trust modeling systems, and show how these optimizations can improve, sometimes significantly, the accuracy of different trust models (in the context of electronic marketplaces). We believe that the proposed techniques will be very useful for trust researchers seeking to improve the accuracy of their own trust models by setting the size and composition of advisor networks. 相似文献
27.
In this paper, we describe an implementation of use in demonstrating the effectiveness of architectures for real-time multi-agent
systems. The implementation provides a simulation of a simplified RoboCup Search and Rescue environment, with unexpected events,
and includes a simulator for both a real-time operating system and a CPU. We present experimental evidence to demonstrate
the benefit of the implementation in the context of a particular hybrid architecture for multi-agent systems that allows certain
agents to remain fully autonomous, while others are fully controlled by a coordinating agent. In addition, we discuss the
value of the implementation for testing any models for the construction of real-time multi-agent systems and include a comparison
to related work.
相似文献
Robin CohenEmail: |
28.
The purpose of this study was to examine individual differences in the effectiveness of learning objects in secondary school classrooms. Specifically, gender, age, grade, subject area, and computer comfort (self-efficacy) were examined in 850 students. Effectiveness was measured in terms of student attitude (learning, quality, and engagement) and student performance. No gender differences were observed between males and females with respect to student attitudes or performance. Age was significantly correlated with student attitudes and performance, however correlation coefficients were small. Grade 12 students were more positive about learning objects and performed better than grade 9 and 10 students. Science students had significantly more positive attitudes and performed better than mathematics students. Finally, students who were more comfortable about computers, appreciated learning objects more than their less confident peers, however performance was unaffected. 相似文献
29.
Selecting the incorrect control during the operation of underground bolting and drilling equipment causes serious injuries. Shape coding and the layout of dual control banks are two aspects of control design which require further examination. The aims of this research were: (i) to determine whether arbitrary shape coding was effective in reducing selection error rates in a virtual analogy of roof-bolting; and (ii) to determine whether any advantages exist for mirror or place layouts for dual control situations in this situation. Two experiments were conducted to address these questions. No benefits of arbitrary shape coding were evident while control location remained constant. When control location was altered, shape coding did provide a significant reduction in selection error rate. No differences between mirror or place arrangements were detected and this question remains open. 相似文献
30.
Yiling Chen Stanko Dimitrov Rahul Sami Daniel M. Reeves David M. Pennock Robin D. Hanson Lance Fortnow Rica Gonen 《Algorithmica》2010,58(4):930-969
We study the equilibrium behavior of informed traders interacting with market scoring rule (MSR) market makers. One attractive feature of MSR is that it is myopically incentive compatible: it is optimal for traders to report their true beliefs about the likelihood of an event outcome provided that they ignore
the impact of their reports on the profit they might garner from future trades. In this paper, we analyze non-myopic strategies
and examine what information structures lead to truthful betting by traders. Specifically, we analyze the behavior of risk-neutral
traders with incomplete information playing in a dynamic game. We consider finite-stage and infinite-stage game models. For
each model, we study the logarithmic market scoring rule (LMSR) with two different information structures: conditionally independent
signals and (unconditionally) independent signals. In the finite-stage model, when signals of traders are independent conditional
on the state of the world, truthful betting is a Perfect Bayesian Equilibrium (PBE). Moreover, it is the unique Weak Perfect
Bayesian Equilibrium (WPBE) of the game. In contrast, when signals of traders are unconditionally independent, truthful betting
is not a WPBE. In the infinite-stage model with unconditionally independent signals, there does not exist an equilibrium in which
all information is revealed in a finite amount of time. We propose a simple discounted market scoring rule that reduces the
opportunity for bluffing strategies. We show that in any WPBE for the infinite-stage market with discounting, the market price
converges to the fully-revealing price, and the rate of convergence can be bounded in terms of the discounting parameter.
When signals are conditionally independent, truthful betting is the unique WPBE for the infinite-stage market with and without
discounting. 相似文献