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关键词： Task analysis   Storms   Scheduling   Instruction sets   Schedules   Computer science   Technological innovation   Distributed stream processing   tuple scheduling   straggler task   backlog balancing  

摘要： Low latency stream processing on large clusters consisting of hundreds to thousands of servers is an increasingly important challenge. A crucial barrier to tackling this challenge is stragglers, i.e., tasks that are significantly straggling behind others in processing the stream data. However, prior straggler mitigation solutions have significant limitations. They balance streaming workloads among tasks but may incur imbalanced backlogs when the workloads exhibit variance, causing stragglers as well. Fortunately, we observe that carefully scheduling the outgoing tuples of different tasks can yield benefits for balancing backlogs, and thus avoids stragglers. To this end, we present Hone, a tuple scheduler that aims to minimize the maximum queue backlog of all tasks over time. Hone leverages an online Largest-Backlog-First (LBF) algorithm with a provable good competitive ratio to perform efficient tuple scheduling. We have implemented Hone based on Apache Storm and evaluated it extensively via both simulations and testbed experiments. Our results show that under the same workload balancing strategy-shuffle grouping, Hone outperforms the original Storm significantly, with the end-to-end tuple processing latency reduced by 78.7 percent on average.

关键词： Optimization   Operations Research/Decision Theory   Real Functions   Computer Science   general  

摘要： Let O be a set of k orientations in the plane, and let P be a simple polygon in the plane. Given two points p, q inside P, we say that p O-sees q if there is an O-staircase contained in P that connects p and q. The O-Kernel of the polygon P, denoted by O-Kernel (P), is the subset of points of P which O-see all the other points in P. This work initiates the study of the computation and maintenance of O-Kernel (P) as we rotate the set O by an angle theta, denoted by O-Kernel(theta) (P). In particular, we consider the case when the set O is formed by either one or two orthogonal orientations, O = {0 degrees} or O = {0 degrees, 90 degrees}. For these cases and P being a simple polygon, we design efficient algorithms for computing the O-Kernel(theta) (P) while theta varies in [-pi/2, pi/2), obtaining: (i) the intervals of angle theta where O-Kernel(theta) (P) is not empty, (ii) a value of angle theta where O-Kernel(theta) (P) optimizes area or perimeter. Further, we show how the algorithms can be improved when P is a simple orthogonal polygon. In addition, our results are extended to the case of a set O = {alpha(1), ..., alpha(k)}.

关键词： Mineral Resources   Fossil Fuels (incl. Carbon Capture)   Geography   general   Sustainable Development   Statistics for Engineering   Physics   Computer Science   Chemistry and Earth Sciences   Mathematical Modeling and Industrial Mathematics  

关键词： Computer Science   general   Computer Hardware   Computer Systems Organization and Communication Networks   Software Engineering/Programming and Operating Systems   Data Structures and Information Theory  

摘要： Zusammenfassung Digitale Ethik wird derzeit weltweit als eine Notwendigkeit diskutiert, um verlässlichere IT-Systeme zu schaffen. Diese Diskussion, geschürt durch die Angst vor einer unkontrollierbaren generellen Künstlichen Intelligenz (KI) und angeheizt von ethischen Dilemmata bestehender Systeme, hat viele Institutionen und Wissenschaftler dazu bewegt, Werteprinzipien einzufordern, an denen sich die Entwicklung komplexer Systeme zukünftig orientieren sollte. Diese inkludieren i. d. R. die Forderung nach Privatsphäre, Sicherheit, Transparenz, Fairness etc. In diesem Artikel wird dargestellt, warum das Abarbeiten von Wertelisten für eine gute bzw. ethisch legitimierte Systementwicklung unzureichend ist. Es wird gezeigt, wie stattdessen ein wirklich ethisches „Value-based Engineering“ aussehen müsste, damit technische Produktinnovationen insgesamt auf bessere (ethischere) Füße gestellt werden. Value-based Engineering (VbE) ist eine prozessgetriebene, ganzheitliche Herangehensweise an die Systementwicklung, die zunächst aus den Ideen des Value Sensitive Designs und dem Ethical Computing schöpfte. Ab 2016 wurde VbE im IEEE 7000 Standard weiter konkretisiert. 10 Prinzipien für ethisch angeleitete Systeminnovation fassen wesentliche Handlungsanforderungen für Unternehmen zusammen.

关键词： Optimization   Shape   Geometry   Convergence   Computer science   Steady-state   Evolutionary computation   Island model   multiobjective optimization   quality indicators (QIs)   selection mechanism  

摘要： For almost 20 years, quality indicators (QIs) have promoted the design of new selection mechanisms of multiobjective evolutionary algorithms (MOEAs). Each indicator-based MOEA (IB-MOEA) has specific search preferences related to its baseline QI, producing Pareto front approximations with different properties. In consequence, an IB-MOEA based on a single QI has a limited scope of multiobjective optimization problems (MOPs) in which it is expected to have a good performance. This issue is emphasized when the associated Pareto front geometries are highly irregular. In order to overcome these issues, we propose here an island-based multiindicator algorithm (IMIA) that takes advantage of the search biases of multiple IB-MOEAs through a cooperative scheme. Our experimental results show that the cooperation of multiple IB-MOEAs allows IMIA to perform more robustly (considering several QIs) than the panmictic versions of its baseline IB-MOEAs as well as several state-of-the-art MOEAs. Additionally, IMIA shows a Pareto-front-shape invariance property, which makes it a remarkable optimizer when tackling MOPs with complex Pareto front geometries.

关键词： User Interfaces and Human Computer Interaction   Computer Science   general   Personal Computing   Mobile Computing  

摘要： Audio description is an accessibility service used by blind or visually impaired individuals. Often accompanying movies, television shows, and other visual art forms, the service provides spoken descriptions of visual content, allowing people with vision loss the ability to access information that sighted people obtain visually. At live theatrical events, audio description provides spoken descriptions of scenes, characters, props, and other visual elements that those with vision loss may otherwise find inaccessible. This paper explores a novel approach to automate the creation and deployment of audio description for repeatable live theatrical events, both musical and non-musical. Using readily available tools and established sound-processing techniques, we describe a framework to automate several aspects of audio description for theater. The method uses a reference audio recording and an online time warping algorithm to align audio description with live performances, including a process for handling unexpected interruptions. We also show how a reference audio recording and descriptive tracks can be generated automatically from a show's script and used to facilitate the deployment of audio description without sufficient resources for multiple performances or a live audio describer. Finally, a software implementation that is integrated into an existing theatrical workflow is also described. This system is used in three evaluation experiments that show the method successfully aligns multiple recordings of works of musical theater and non-musical plays in order to automatically trigger pre-recorded, descriptive audio in real time.

关键词： high-incidence disabilities   teacher beliefs   teacher knowledge   assistive technology   teacher preparation practices and outcomes  

摘要： Increasingly in K-12 schools, students are gaining access to computational thinking (CT) and computer science (CS). This access, however, is not always extended to students with disabilities. One way to increase CT and CS (CT/CS) exposure for students with disabilities is through preparing special education teachers to do so. In this study, researchers explore exposing special education preservice teachers to the ideas of CT/CS in the context of a mathematics methods course for students with disabilities or those at risk of disability. Through analyzing lesson plans and reflections from 31 preservice special education teachers, the researchers learned that overall emerging promise exists with regard to the limited exposure of preservice special education teachers to CT/CS in mathematics. Specifically, preservice teachers demonstrated the ability to include CT/CS in math lesson plans and showed understanding of how CT/CS might enhance instruction with students with disabilities via reflections on these lessons. The researchers, however, also found a need for increased experiences and opportunities for preservice special education teachers with CT/CS to more positively impact access for students with disabilities.

关键词： User Interfaces and Human Computer Interaction   Computer Science   general   Personal Computing   Mobile Computing  

关键词： Gamification   Computer science   Gender differences   Education  

摘要： Underrepresentation of women in computer science (CS) increasingly demands the necessity to find and enhance current learning engagement approaches to bring more women into computing fields. Some researchers have been exploring the influence of gamification on female students as one of these possible learning engagement strategies. Gamification refers to the introduction of video game elements into non-game activities to enhance engagement and motivation. Previous studies have reported mixed results of the impact of gamification on women. In this study, we introduce SEP-CyLE (Software Engineering and Programming Cyberlearning Environment), an online gamified tool that was designed to provide supplemental computing content to students. This paper presents a convergent mixed-methods study guided by social identity theory and self-efficacy to understand women's experiences with this gamified tool. More specifically, this study explores virtual points' and leaderboards' effects on CS identity development, self-efficacy, and performance. The results show that virtual points and the leaderboard contributed to improved performance for students of all genders, suggesting that gamification is a gender-neutral learning engagement strategy that improves female students' performance as much as male students. Regardless of improved performance, most women did not actively enjoy or were motivated by the virtual points or leaderboard in SEP-CyLE. Additionally, gamification had no significant impact on CS identity development or self-efficacy constructs and had little to no impact on women's interest and engagement in the field of computing.

关键词： ethics   higher education   human‐   centred analytics   multimodal learning analytics   pervasive surveillance   privacy   thematic analysis  

摘要： Multimodal data have the potential to explore emerging learning practices that extend human cognitive capacities. A critical issue stretching in many multimodal learning analytics (MLA) systems and studies is the current focus aimed at supporting researchers to model learner behaviours, rather than directly supporting learners. Moreover, many MLA systems are designed and deployed without learners' involvement. We argue that in order to create MLA interfaces that directly support learning, we need to gain an expanded understanding of how multimodal data can support learners' authentic needs. We present a qualitative study in which 40 computer science students were tracked in an authentic learning activity using wearable and static sensors. Our findings outline learners' curated representations about multimodal data and the non-technical challenges in using these data in their learning practice. The paper discusses 10 dimensions that can serve as guidelines for researchers and designers to create effective and ethically aware student-facing MLA innovations.