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  • Gharaee, Zahra (författare)
  • Action in Mind : A Neural Network Approach to Action Recognition and Segmentation
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Recognizing and categorizing human actions is an important task with applications in various fields such as human-robot interaction, video analysis, surveillance, video retrieval, health care system and entertainment industry.This thesis presents a novel computational approach for human action recognition through different implementations of multi-layer architectures based on artificial neural networks. Each system level development is designed to solve different aspects of the action recognition problem including online real-time processing, action segmentation and the involvement of objects. The analysis of the experimentalresults are illustrated and described in six articles.The proposed action recognition architecture of this thesis is composed of several processing layers including a preprocessing layer, an ordered vector representation layer and three layers of neural networks.It utilizes self-organizing neural networks such as Kohonen feature maps and growing grids as the main neural network layers. Thus the architecture presents a biological plausible approach with certain features such as topographic organization of the neurons, lateral interactions, semi-supervised learning and the ability to represent high dimensional input space in lower dimensional maps.For each level of development the system is trained with the input data consisting of consecutive 3D body postures and tested with generalized input data that the system has never met before. The experimental results of different system level developments show that the system performs well with quite high accuracy for recognizing human actions.
  • Mealier, Anne Laure, et al. (författare)
  • Construals of meaning : The role of attention in robotic language production
  • 2016
  • Ingår i: Interaction Studies. - : John Benjamins Publishing Company. - 1572-0373. ; 17:1, s. 48-76
  • Forskningsöversikt (refereegranskat)abstract
    • In robotics research with language-based interaction, simplifications are made, such that a given event can be described in a unique manner, where there is a direct mapping between event representations and sentences that can describe these events. However, common experience tells us that the same physical event can be described in multiple ways, depending on the perspective of the speaker. The current research develops methods for representing events from multiple perspectives, and for choosing the perspective that will be used for generating a linguistic construal, based on attentional processes in the system. The multiple perspectives are based on the principle that events can be considered in terms of the force driving the event, and the result obtained from the event, based on the theory of Godenfors. In addition, within these perspectives a further refinement can be made with respect to the agent, object, and recipient perspectives. We develop a system for generating appropriate construals of meaning, and demonstrate how this can be used in a realistic dialogic interaction between a behaving robot and a human interlocutor.
  • Ackermann, Hilmar, et al. (författare)
  • A Backend Extension Mechanism for PQL/Java with Free Run-Time Optimisation
  • 2015
  • Ingår i: Compiler Construction,Lond, United Kingdom,2015-04-11 - 2015-04-18. - : Springer. ; 9031, s. 111-130
  • Konferensbidrag (refereegranskat)abstract
    • In many data processing tasks, declarative query programming offers substantial benefit over manual data analysis: the query processors found in declarative systems can use powerful algorithms such as query planning to choose high-level execution strategies during compilation. However, the principal downside of such languages is that their primitives must be carefully curated, to allow the query planner to correctly estimate their overhead. In this paper, we examine this challenge in one such system, PQL/Java. PQL/Java adds a powerful declarative query language to Java to enable and automatically parallelise queries over the Java heap. In the past, the language has not provided any support for custom user-designed datatypes, as such support requires complex interactions with its query planner and backend.We examine PQL/Java and its intermediate language in detail and describe a new system that simplifies PQL/Java extensions. This system provides a language that permits users to add new primitives with arbitrary Java computations, and new rewriting rules for optimisation. Our system automatically stages compilation and exploits constant information for dead code elimination and type specialisation. We have re-written our PQL/Java backend in our extension language, enabling dynamic and staged compilation.We demonstrate the effectiveness of our extension language in several case studies, including the efficient integration of SQL queries, and by analysing the run-time performance of our rewritten prototype backend.
  • Bagge Carlson, Fredrik (författare)
  • MonteCarloMeasurements.jl : Propagation of distributions by Monte-Carlo sampling: Real number types with uncertainty represented by particle clouds.
  • Annan publikation (övrigt vetenskapligt)abstract
    • This package facilitates working with probability distributions by means of Monte-Carlo methods, in a way that allows for propagation of probability distributions through functions. This is useful for, e.g., nonlinear uncertainty propagation. A variable or parameter might be associated with uncertainty if it is measured or otherwise estimated from data. We provide two core types to represent probability distributions: Particles and StaticParticles, both <: Real. (The name "Particles" comes from the particle-filtering literature.) These types all form a Monte-Carlo approximation of the distribution of a floating point number, i.e., the distribution is represented by samples/particles. Correlated quantities are handled as well, see multivariate particles below. Although several interesting use cases for doing calculations with probability distributions have popped up (see Examples), the original goal of the package is similar to that of Measurements.jl, to propagate the uncertainty from input of a function to the output. The difference compared to a Measurement is that Particles represent the distribution using a vector of unweighted particles, and can thus represent arbitrary distributions and handle nonlinear uncertainty propagation well. Functions like f(x) = x², f(x) = sign(x) at x=0 and long-time integration, are examples that are not handled well using linear uncertainty propagation ala Measurements.jl. MonteCarloMeasurements also support correlations between quantities. A number of type Particles behaves just as any other Number while partaking in calculations. After a calculation, an approximation to the complete distribution of the output is captured and represented by the output particles. mean, std etc. can be extracted from the particles using the corresponding functions. Particles also interact with Distributions.jl, so that you can call, e.g., Normal(p) and get back a Normal type from distributions or fit(Gamma, p) to get a Gammadistribution. Particles can also be iterated, asked for maximum/minimum, quantile etc. If particles are plotted with plot(p), a histogram is displayed. This requires Plots.jl. A kernel-density estimate can be obtained by density(p) is StatsPlots.jl is loaded.
  • Borg, Markus (författare)
  • Do Preparatory Programming Lab Sessions Contribute to Even Work Distribution in Student Teams?
  • Ingår i: 42nd International Conference on Software Engineering (ICSE),Seoul, Korea, Republic of,2020-07-06 - 2020-07-11. - : IEEE Computer Society. ; , s. 254-255
  • Konferensbidrag (refereegranskat)abstract
    • Unfair work distribution is common in project-based learning with teams of students. One contributing factor is that students are differently skilled developers. To mitigate the differences in a course with group work, we introduced mandatory programming lab sessions. The intervention did not affect the work distribution, showing that more is needed to balance the workload. Contrary to our goal, the intervention was very well received among experienced students, but unpopular with students weak at programming.
  • Heintz, Fredrik, et al. (författare)
  • Computing at School in Sweden - Experiences from Introducing Computer Science within Existing Subjects
  • 2015
  • Ingår i: 8th International Conference on Informatics in Schools: Situation, Evolution, and Perspectives,Ljubljana, Slovenia,2015-09-28 - 2015-10-01. - : Springer. ; 9378, s. 118-130
  • Konferensbidrag (refereegranskat)abstract
    • Computing is no longer considered a subject area only relevant for a narrow group of professionals, but rather as a vital part of general education that should be available to all children and youth. Since making changes to national curricula takes time, people are trying to find other ways of introducing children and youth to computing. In Sweden, several current initiatives by researchers and teachers aim at finding ways of working with computing within the current curriculum. In this paper we present case studies based on a selection of these initiatives from four major regions in Sweden and based on these case studies we present our ideas for how to move forward on introducing computational thinking on a larger scale in Swedish education.
  • Johnsson, Björn A, et al. (författare)
  • Evaluating a Dynamic Keep-Alive Messaging Strategy for Mobile Pervasive Systems
  • 2017
  • Ingår i: The 8th International Conference on Ambient Systems, Networks and Technologies,Madeira, Portugal,2017-05-16 - 2017-05-19. - : Elsevier. ; 109, s. 319-326
  • Tidskriftsartikel (refereegranskat)abstract
    • Timely loss-of-contact detection between devices in pervasive systems using mobile networks is an important aspect for both functionality and user experience. Traditional schemes where time-to-live is defined by the service provider are not adequate in mobile networks where communication failures are frequent. On the other hand, schemes using keep-alive messaging tend to increase the communication overhead, in particular if the time to detect a loss of contact needs to be short. We introduce a strategy where the time between keep-alive messages is adjusted dynamically according to the need in a particular application. Our solution was evaluated with usage data from a professional application built on the PalCom framework. The measurements show a 96 % decrease of the communication overhead while still maintaining the same system responsiveness.
  • Åkesson, Alfred (författare)
  • ComPOS - a development environment for composing internet-of-things services
  • 2019
  • Licentiatavhandling (övrigt vetenskapligt)abstract
    • Internet-of-things (IoT) systems consist of spatially distributed devices with services. Compared to desktop applications, IoT systems are always running and need to deal with unresponsive devices and weak connectivity. In this thesis, we examine the following question: How can we simplify the development of IoT systems? We begin to answer this question by proposing a domain-specific language (DSL), called ComPOS, for composing IoT services. In the DSL, the user specifies the reaction to a message. The reaction can be programmed to request and receive responses in sequence and parallel. ComPOS can abort a running reaction when a new message arrives; this is to support unresponsive devices and weak connectivity. We demonstrate our language by creating a bird-spying system that takes photos of a garden and then stores the ones containing a bird. The ComPOS editor supports live programming for programming a running system. Programming in our DSL is divided into three phases: finding services (explore), composing services (assemble), and abstracting compositions as new services (expose). When developing a DSL, it takes effort specifying the syntax and semantics, building the editor, and integrating with the middleware. To reduce the effort needed to experiment with our DSL, we have created a tool called Jatte. The tool is a generic projectional editor that can be tuned for different languages using attribute grammars. We have integrated the editor built with the tool into an IoT development environment supporting discovery of devices and services.
  • Johnsson, Björn A., et al. (författare)
  • Towards end-user development of graphical user interfaces for internet of things
  • 2020
  • Ingår i: Future Generation Computer Systems. - : Elsevier. - 0167-739X.
  • Tidskriftsartikel (refereegranskat)abstract
    • Graphical user interface (GUI) development is generally complicated, time-consuming, and requires programming knowledge. In the context of the internet of things, this work focuses on producing an efficient development approach that also supports non-experts. We introduce a novel "inverted" development approach that does not require program code to be written - a step towards supporting end-user development in the given context. The approach is realized as a language for describing GUIs, interpreters for rendering GUIs, and a graphical tool for creating and editing GUIs. The work is evaluated in a number of research projects in the domain of e-health; we conclude that the GUI language is practically viable for building professional-grade GUIs. Furthermore, the presented editor is compared directly to a market leading product in a controlled experiment. From this, we conclude that the editor is accessible to new users, and that it can be more efficient to use than the commercial alternative.
  • Justesen, Niels, et al. (författare)
  • Playing Multi-Action Adversarial Games : Online Evolutionary Planning versus Tree Search
  • Ingår i: IEEE Transactions on Games. - : Institute of Electrical and Electronics Engineers Inc.. - 2475-1502. ; 10:3, s. 281-291
  • Tidskriftsartikel (refereegranskat)abstract
    • We address the problem of playing turn-based multi-action adversarial games, which include many strategy games with extremely high branching factors as players take multiple actions each turn. This leads to the breakdown of standard tree search methods, including Monte Carlo Tree Search (MCTS), as they become unable to reach a sufficient depth in the game tree. In this paper we introduce Online Evolutionary Planning (OEP) to address this challenge, which searches for combinations of actions to perform during a single turn guided by a fitness function that evaluates the quality of a particular state. We compare OEP to different MCTS variations that constrain the exploration to deal with the high branching factor in the turn-based multi-action game Hero Academy. While the constrained MCTS variations outperform the vanilla MCTS implementation by a large margin, OEP is able to search the space of plans more efficiently than any of the tested tree search methods as it has a relative advantage when the number of actions per turn increases.
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