| 1. |
- Wilhelmsson, Kenneth, 1976
(författare)
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Huvudansatser för parsningsmetoder. Om programutvecklingens förutsättningar i en svensk kontext
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Syftet med denna text var att ge en inblick i området (syntaktisk) parsning. Tanken var att ge en bild av utvecklingen som var 1) fri från alltför tekniska detaljer, då området är programmeringstekniskt, och 2) beskriven ur ett svenskt perspektiv. Bakgrunden till valet av ämne till texten, som var tänkt att finnas med i antologin Text och kontext, var att parsning är relativt okänt för många personer verksamma inom närliggande områden, samtidigt som det är ett absolut nyckelbegrepp för den som ägnar sig åt datorlingvistik eller språkteknologi. Målet var alltså att ge en ganska allmän utifrånblick på några centrala sidor av utvecklingen, samtidigt som det tydligt är så att den som själv arbetat med utveckling kan ha starka åsikter och preferenser rörande metodval, något som i ärlighetens namn kanske inte heller denna text är lösgjord från. Hur ska det göras? Konsten att utveckla automatisk syntaxanalys av naturlig text kan läras ut från ett flertal perspektiv. Det kan t.ex. ske med fokus på användandet av en viss grammatikformalism, med fokus på beräkningssnabbhet, med fokus på entydiggörande av möjliga ambiguiteter. Tolkningsval kan göras med hjälp av antingen handskrivna regler eller inhämtad statistik. En sorts huvudtema i denna text är hur metoder för parsning på senare år uppvisar förändringar som kanske kan förklaras med att programmen har fått andra användningsområden och att metoderna har anpassats därefter (en annan tolkning är att flera senare system inte längre gör parsning i strikt mening). När detta tänkta ”kapitel” var färdigt fick det kommentaren att det inte var anpassat för antologins målgrupp. Det fick skrivas en annan kapiteltext, men det kom samtidigt ett förslag att publicera texten om parsning här som denna rapport.
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| 2. |
- Wilhelmsson, Kenneth, 1976
(författare)
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Autentiska och artificiella frågor till svensk text Automatisk frågegenerering jämfört med användares frågor för informationsåtkomst : Authentic and artificial questions to Swedish text Automatically generated questions versus user-generated questions for information access
- 2015
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Informationssökning mot ostrukturerade datakällor som fri text är ett av de områden där användargränssnitt med fri formulering i naturligt språk har tagits fram. I ett sådant, eventuellt AI-betonat, system kan några grundläggande svårigheter från användarperspektivet märkas. En sådan svårighet är att en användare inte känner till huruvida en fråga som hon avser att ställa egentligen kan besvaras av den aktuella texten. Denna svårighet, tillsammans med andra, som de kraftiga variationsmöjligheterna för formen för ett giltigt svar på en ställd fråga, riskerar att leda till att användarintrycken av systemtypen blir negativa. De moment som behöver ingå i ett sådant frågebaserat informationssystems funktionssätt måste på något sätt inbegripa en mappning av frågeled i frågan (t.ex. när) till den form och grammatisk funktion som svaret i texten måste ha (för frågan när normalt ett tidsadverbial). Bland annat denna iakttagelse inbjuder till användning av automatisk frågegenerering (question generation, QG). Frågegenerering innebär att frågor som en naturlig text besvarar initialt utvinns av ett program som samlar in dem i explicit form. Tanken för användning i informationssökning är att en användare i gränssnittet enbart ska kunna ställa just dessa frågor, vilka faktiskt besvaras av texten. Denna studie gäller just de frågor som ett automatiskt frågegenereringssystem för svenska kan, och genom vidare utveckling, skulle kunna generera för godtycklig digital svensk text. Även om mängden automatiskt genererade frågor och frågeformuleringar kan bli mycket stor, utrymmesmässigt många gånger större än ursprungstexten, så är det tydligt att den beskrivna metoden för frågegenerering för svenska inte kan och troligen inte heller kommer att kunna förmås att skapa alla de frågor och frågeformuleringar som en vanlig användare skulle anse att en viss text besvarar. Men hur väl fungerar då automatiskt genererade frågor i detta sammanhang? Denna uppsats kretsar kring en användarundersökning där undersökningsdeltagare har ombetts att formulera frågor som texter besvarar, och som anses vara relevanta frågor. Den resulterande samlingen frågor undersöktes och kategoriserades. Resultatet av undersökningens huvudfråga visar att bara 20-25 % av användarnas frågeformuleringar skulle kunna genereras direkt automatiskt med aktuell ansats – utan vissa informationstekniska förbättringar. Uppsatsen föreslår viss ny terminologi för detta outforskade område, bl.a. för att skilja mellan de olika grader av processkrav som generering av olika frågeslag från text kräver.
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| 3. |
- Chatterjee, Bapi, 1982
(författare)
-
Lock-free Concurrent Search
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The contemporary computers typically consist of multiple computing cores with high compute power. Such computers make excellent concurrent asynchronous shared memory system. On the other hand, though many celebrated books on data structure and algorithm provide a comprehensive study of sequential search data structures, unfortunately, we do not have such a luxury if concurrency comes in the setting. The present dissertation aims to address this paucity. We describe novel lock-free algorithms for concurrent data structures that target a variety of search problems. (i) Point search (membership query, predecessor query, nearest neighbour query) for 1-dimensional data: Lock-free linked-list; lock-free internal and external binary search trees (BST). (ii) Range search for 1-dimensional data: A range search method for lock-free ordered set data structures - linked-list, skip-list and BST. (iii) Point search for multi-dimensional data: Lock-free kD-tree, specially, a generic method for nearest neighbour search. We prove that the presented algorithms are linearizable i.e. the concurrent data structure operations intuitively display their sequential behaviour to an observer of the concurrent system. The lock-freedom in the introduced algorithms guarantee overall progress in an asynchronous shared memory system. We present the amortized analysis of lock-free data structures to show their efficiency. Moreover, we provide sample implementations of the algorithms and test them over extensive micro-benchmarks. Our experiments demonstrate that the implementations are scalable and perform well when compared to related existing alternative implementations on common multi-core computers. Our focus is on propounding the generic methodologies for efficient lock-free concurrent search. In this direction, we present the notion of help-optimality, which captures the optimization of amortized step complexity of the operations. In addition to that, we explore the language-portable design of lock-free data structures that aims to simplify an implementation from programmer’s point of view. Finally, our techniques to implement lock-free linearizable range search and nearest neighbour search are independent of the underlying data structures and thus are adaptive to similar data structures.
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| 4. |
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| 5. |
- Yun, Yixiao, 1987, et al.
(författare)
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Maximum-Likelihood Object Tracking from Multi-View Video by Combining Homography and Epipolar Constraints
- 2012
-
Ingår i: 6th ACM/IEEE Int'l Conf on Distributed Smart Cameras (ICDSC 12), Oct 30 - Nov.2, 2012, Hong Kong. - 9781450317726 ; , s. 6 pages-
-
Konferensbidrag (refereegranskat)abstract
- This paper addresses problem of object tracking in occlusion scenarios, where multiple uncalibrated cameras with overlapping fields of view are used. We propose a novel method where tracking is first done independently for each view and then tracking results are mapped between each pair of views to improve the tracking in individual views, under the assumptions that objects are not occluded in all views and move uprightly on a planar ground which may induce a homography relation between each pair of views. The tracking results are mapped by jointly exploiting the geometric constraints of homography, epipolar and vertical vanishing point. Main contributions of this paper include: (a) formulate a reference model of multi-view object appearance using region covariance for each view; (b) define a likelihood measure based on geodesics on a Riemannian manifold that is consistent with the destination view by mapping both the estimated positions and appearances of tracked object from other views; (c) locate object in each individual view based on maximum likelihood criterion from multi-view estimations of object position. Experiments have been conducted on videos from multiple uncalibrated cameras, where targets experience long-term partial or full occlusions. Comparison with two existing methods and performance evaluations are also made. Test results have shown effectiveness of the proposed method in terms of robustness against tracking drifts caused by occlusions.
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| 6. |
- Rumman, Nadine Abu, et al.
(författare)
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Skin deformation methods for interactive character animation
- 2017
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Ingår i: Communications in Computer and Information Science. - Cham : Springer International Publishing. - 1865-0937 .- 1865-0929. ; 693, s. 153-174, s. 153-174
-
Konferensbidrag (refereegranskat)abstract
- Character animation is a vital component of contemporary computer games, animated feature films and virtual reality applications. The problem of creating appealing character animation can best be described by the title of the animation bible: “The Illusion of Life”. The focus is not on completing a given motion task, but more importantly on how this motion task is performed by the character. This does not necessarily require realistic behavior, but behavior that is believable. This of course includes the skin deformations when the character is moving. In this paper, we focus on the existing research in the area of skin deformation, ranging from skeleton-based deformation and volume preserving techniques to physically based skinning methods. We also summarize the recent contributions in deformable and soft body simulations for articulated characters, and discuss various geometric and example-based approaches. © Springer International Publishing AG 2017.
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| 7. |
- Scheuner, Joel, 1991, et al.
(författare)
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Performance Benchmarking of Infrastructure-as-a-Service (IaaS) Clouds with CloudWorkBench
- 2019
-
Ingår i: ICPE 2019 - Companion of the 2019 ACM/SPEC International Conference on Performance Engineering. - New York, NY, USA : ACM. ; , s. 53-56
-
Konferensbidrag (refereegranskat)abstract
- The continuing growth of the cloud computing market has led to an unprecedented diversity of cloud services with different performance characteristics. To support service selection, researchers and practitioners conduct cloud performance benchmarking by measuring and objectively comparing the performance of different providers and configurations (e.g., instance types in different data center regions). In this tutorial, we demonstrate how to write performance tests for IaaS clouds using the Web-based benchmarking tool Cloud WorkBench (CWB). We will motivate and introduce benchmarking of IaaS cloud in general, demonstrate the execution of a simple benchmark in a public cloud environment, summarize the CWB tool architecture, and interactively develop and deploy a more advanced benchmark together with the participants.
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| 8. |
- Lu, Zhihan, et al.
(författare)
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Multimodal Hand and Foot Gesture Interaction for Handheld Devices
- 2014
-
Ingår i: ACM Transactions on Multimedia Computing, Communications, and Applications (TOMCCAP). - : Association for Computing Machinery (ACM). - 1551-6857 .- 1551-6865. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- We present a hand-and-foot-based multimodal interaction approach for handheld devices. Our method combines input modalities (i.e., hand and foot) and provides a coordinated output to both modalities along with audio and video. Human foot gesture is detected and tracked using contour-based template detection (CTD) and Tracking-Learning-Detection (TLD) algorithm. 3D foot pose is estimated from passive homography matrix of the camera. 3D stereoscopic and vibrotactile are used to enhance the immersive feeling. We developed a multimodal football game based on the multimodal approach as a proof-of-concept. We confirm our systems user satisfaction through a user study.
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| 9. |
- Bainomugisha, Engineer, et al.
(författare)
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Message from Chairs of SEiA 2018
- 2018
-
Ingår i: Proceedings - International Conference on Software Engineering. - New York, NY, USA : ACM. - 0270-5257. ; 2018, s. x-xi
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 10. |
- Fröberg, Rikard, 1971, et al.
(författare)
-
Introduction to Databases
- 2018
-
Bok (övrigt vetenskapligt/konstnärligt)abstract
- Kurlitteratur för bland annat 7,5 hp databaser (delkurs i TIG058 programmeringsteknik och databaser). Kurlitteraturen (läromedlet) består av texter, exempel, övningar, föreläsningspresentationer, videoföreläsningar: Antal slidesidor193 Tid per slidesida i snitt (sv):0:00:56 Antal slides:15 Total tid eng. video:1:24:44 Total tid sv. video:2:46:39 Totalt antal övningar/frågor85 Totalt antal A4-sidor med övningar69 Totalt antal A4-sidor med text och exempel73 Totalt antal A4-sidor med text och övningar142 Materialet underhålls och utvecklas kontinuerligt. Senaste upplaga är från 2018.
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| 11. |
- Laaber, C., et al.
(författare)
-
An Evaluation of Open-Source Software Microbenchmark Suites for Continuous Performance Assessment
- 2018
-
Ingår i: MSR '18 Proceedings of the 15th International Conference on Mining Software Repositories. - New York, NY, USA : ACM Digital Library. - 9781450357166 ; , s. 119-130, s. 119-130
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Continuous integration (CI) emphasizes quick feedback to developers. This is at odds with current practice of performance testing, which predominantely focuses on long-running tests against entire systems in production-like environments. Alternatively, software microbenchmarking attempts to establish a performance baseline for small code fragments in short time. This paper investigates the quality of microbenchmark suites with a focus on suitability to deliver quick performance feedback and CI integration. We study ten open-source libraries written in Java and Go with benchmark suite sizes ranging from 16 to 983 tests, and runtimes between 11 minutes and 8.75 hours. We show that our study subjects include benchmarks with result variability of 50% or higher, indicating that not all benchmarks are useful for reliable discovery of slow-downs. We further artificially inject actual slowdowns into public API methods of the study subjects and test whether test suites are able to discover them. We introduce a performance-test quality metric called the API benchmarking score (ABS). ABS represents a benchmark suite's ability to find slowdowns among a set of defined core API methods. Resulting benchmarking scores (i.e., fraction of discovered slowdowns) vary between 10% and 100% for the study subjects. This paper's methodology and results can be used to (1) assess the quality of existing microbenchmark suites, (2) select a set of tests to be run as part of CI, and (3) suggest or generate benchmarks for currently untested parts of an API.
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| 12. |
- Mallozzi, Piergiuseppe, 1990, et al.
(författare)
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A runtime monitoring framework to enforce invariants on reinforcement learning agents exploring complex environments
- 2019
-
Ingår i: RoSE 2019, IEEE/ACM 2nd International Workshop on Robotics Software Engineering, p.5-12. - : IEEE. - 9781728122496
-
Konferensbidrag (refereegranskat)abstract
- © 2019 IEEE. Without prior knowledge of the environment, a software agent can learn to achieve a goal using machine learning. Model-free Reinforcement Learning (RL) can be used to make the agent explore the environment and learn to achieve its goal by trial and error. Discovering effective policies to achieve the goal in a complex environment is a major challenge for RL. Furthermore, in safety-critical applications, such as robotics, an unsafe action may cause catastrophic consequences in the agent or in the environment. In this paper, we present an approach that uses runtime monitoring to prevent the reinforcement learning agent to perform 'wrong' actions and to exploit prior knowledge to smartly explore the environment. Each monitor is de?ned by a property that we want to enforce to the agent and a context. The monitors are orchestrated by a meta-monitor that activates and deactivates them dynamically according to the context in which the agent is learning. We have evaluated our approach by training the agent in randomly generated learning environments. Our results show that our approach blocks the agent from performing dangerous and safety-critical actions in all the generated environments. Besides, our approach helps the agent to achieve its goal faster by providing feedback and shaping its reward during learning.
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| 13. |
- Fu, Keren, et al.
(författare)
-
Deepside: A general deep framework for salient object detection
- 2019
-
Ingår i: Neurocomputing. - : Elsevier BV. - 0925-2312 .- 1872-8286. ; 356, s. 69-82
-
Tidskriftsartikel (refereegranskat)abstract
- Deep learning-based salient object detection techniques have shown impressive results compared to con- ventional saliency detection by handcrafted features. Integrating hierarchical features of Convolutional Neural Networks (CNN) to achieve fine-grained saliency detection is a current trend, and various deep architectures are proposed by researchers, including “skip-layer” architecture, “top-down” architecture, “short-connection” architecture and so on. While these architectures have achieved progressive improve- ment on detection accuracy, it is still unclear about the underlying distinctions and connections between these schemes. In this paper, we review and draw underlying connections between these architectures, and show that they actually could be unified into a general framework, which simply just has side struc- tures with different depths. Based on the idea of designing deeper side structures for better detection accuracy, we propose a unified framework called Deepside that can be deeply supervised to incorporate hierarchical CNN features. Additionally, to fuse multiple side outputs from the network, we propose a novel fusion technique based on segmentation-based pooling, which severs as a built-in component in the CNN architecture and guarantees more accurate boundary details of detected salient objects. The effectiveness of the proposed Deepside scheme against state-of-the-art models is validated on 8 benchmark datasets.
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| 14. |
- Huhnstock, Nikolas Alexander, 1988-, et al.
(författare)
-
An Infinite Replicated Softmax Model for Topic Modeling
- 2019
-
Ingår i: Modeling Decisions for Artificial Intelligence. - Cham : Springer. - 9783030267728 - 9783030267735 ; , s. 307-318
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we describe the infinite replicated Softmax model (iRSM) as an adaptive topic model, utilizing the combination of the infinite restricted Boltzmann machine (iRBM) and the replicated Softmax model (RSM). In our approach, the iRBM extends the RBM by enabling its hidden layer to adapt to the data at hand, while the RSM allows for modeling low-dimensional latent semantic representation from a corpus. The combination of the two results is a method that is able to self-adapt to the number of topics within the document corpus and hence, renders manual identification of the correct number of topics superfluous. We propose a hybrid training approach to effectively improve the performance of the iRSM. An empirical evaluation is performed on a standard data set and the results are compared to the results of a baseline topic model. The results show that the iRSM adapts its hidden layer size to the data and when trained in the proposed hybrid manner outperforms the base RSM model.
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| 15. |
- Kucher, Kostiantyn, et al.
(författare)
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Visual Analysis of Online Social Media to Open Up the Investigation of Stance Phenomena
- 2016
-
Ingår i: Information Visualization. - : Sage Publications. - 1473-8716 .- 1473-8724. ; 15:2, s. 93-116
-
Tidskriftsartikel (refereegranskat)abstract
- Online social media are a perfect text source for stance analysis. Stance in human communication is concerned with speaker attitudes, beliefs, feelings and opinions. Expressions of stance are associated with the speakers' view of what they are talking about and what is up for discussion and negotiation in the intersubjective exchange. Taking stance is thus crucial for the social construction of meaning. Increased knowledge of stance can be useful for many application fields such as business intelligence, security analytics, or social media monitoring. In order to process large amounts of text data for stance analyses, linguists need interactive tools to explore the textual sources as well as the processed data based on computational linguistics techniques. Both original texts and derived data are important for refining the analyses iteratively. In this work, we present a visual analytics tool for online social media text data that can be used to open up the investigation of stance phenomena. Our approach complements traditional linguistic analysis techniques and is based on the analysis of utterances associated with two stance categories: sentiment and certainty. Our contributions include (1) the description of a novel web-based solution for analyzing the use and patterns of stance meanings and expressions in human communication over time; and (2) specialized techniques used for visualizing analysis provenance and corpus overview/navigation. We demonstrate our approach by means of text media on a highly controversial scandal with regard to expressions of anger and provide an expert review from linguists who have been using our tool.
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| 16. |
- Peldszus, Sven, et al.
(författare)
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Secure Data-Flow Compliance Checks between Models and Code Based on Automated Mappings
- 2019
-
Ingår i: Proceedings - 2019 ACM/IEEE 22nd International Conference on Model Driven Engineering Languages and Systems, MODELS 2019. ; , s. 23-33
-
Konferensbidrag (refereegranskat)abstract
- During the development of security-critical software, the system implementation must capture the security properties postulated by the architectural design. This paper presents an approach to support secure data-flow compliance checks between design models and code. To iteratively guide the developer in discovering such compliance violations we introduce automated mappings. These mappings are created by searching for correspondences between a design-level model (Security Data Flow Diagram) and an implementation-level model (Program Model). We limit the search space by considering name similarities between model elements and code elements as well as by the use of heuristic rules for matching data-flow structures. The main contributions of this paper are three-fold. First, the automated mappings support the designer in an early discovery of implementation absence, convergence, and divergence with respect to the planned software design. Second, the mappings also support the discovery of secure data-flow compliance violations in terms of illegal asset flows in the software implementation. Third, we present our implementation of the approach as a publicly available Eclipse plugin and its evaluation on five open source Java projects (including Eclipse secure storage).
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| 17. |
- Aramrattana, Maytheewat, 1988-, et al.
(författare)
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Team Halmstad Approach to Cooperative Driving in the Grand Cooperative Driving Challenge 2016
- 2018
-
Ingår i: IEEE transactions on intelligent transportation systems (Print). - Piscataway, N.J. : Institute of Electrical and Electronics Engineers Inc.. - 1524-9050 .- 1558-0016. ; 19:4, s. 1248-1261
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Tidskriftsartikel (refereegranskat)abstract
- This paper is an experience report of team Halmstad from the participation in a competition organised by the i-GAME project, the Grand Cooperative Driving Challenge 2016. The competition was held in Helmond, The Netherlands, during the last weekend of May 2016. We give an overview of our car’s control and communication system that was developed for the competition following the requirements and specifications of the i-GAME project. In particular, we describe our implementation of cooperative adaptive cruise control, our solution to the communication and logging requirements, as well as the high level decision making support. For the actual competition we did not manage to completely reach all of the goals set out by the organizers as well as ourselves. However, this did not prevent us from outperforming the competition. Moreover, the competition allowed us to collect data for further evaluation of our solutions to cooperative driving. Thus, we discuss what we believe were the strong points of our system, and discuss post-competition evaluation of the developments that were not fully integrated into our system during competition time. © 2000-2011 IEEE.
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| 18. |
- Memedi, Mevludin, 1983-, et al.
(författare)
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Automatic Spiral Analysis for Objective Assessment of Motor Symptoms in Parkinson's Disease
- 2015
-
Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 15:9, s. 23727-23744
-
Tidskriftsartikel (refereegranskat)abstract
- A challenge for the clinical management of advanced Parkinson's disease (PD) patients is the emergence of fluctuations in motor performance, which represents a significant source of disability during activities of daily living of the patients. There is a lack of objective measurement of treatment effects for in-clinic and at-home use that can provide an overview of the treatment response. The objective of this paper was to develop a method for objective quantification of advanced PD motor symptoms related to off episodes and peak dose dyskinesia, using spiral data gathered by a touch screen telemetry device. More specifically, the aim was to objectively characterize motor symptoms (bradykinesia and dyskinesia), to help in automating the process of visual interpretation of movement anomalies in spirals as rated by movement disorder specialists. Digitized upper limb movement data of 65 advanced PD patients and 10 healthy (HE) subjects were recorded as they performed spiral drawing tasks on a touch screen device in their home environment settings. Several spatiotemporal features were extracted from the time series and used as inputs to machine learning methods. The methods were validated against ratings on animated spirals scored by four movement disorder specialists who visually assessed a set of kinematic features and the motor symptom. The ability of the method to discriminate between PD patients and HE subjects and the test-retest reliability of the computed scores were also evaluated. Computed scores correlated well with mean visual ratings of individual kinematic features. The best performing classifier (Multilayer Perceptron) classified the motor symptom (bradykinesia or dyskinesia) with an accuracy of 84% and area under the receiver operating characteristics curve of 0.86 in relation to visual classifications of the raters. In addition, the method provided high discriminating power when distinguishing between PD patients and HE subjects as well as had good test-retest reliability. This study demonstrated the potential of using digital spiral analysis for objective quantification of PD-specific and/or treatment-induced motor symptoms.
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| 19. |
- Sandklef, Henrik, 1971, et al.
(författare)
-
Programming with Java
- 2017
-
Bok (övrigt vetenskapligt/konstnärligt)abstract
- Course literature in programming with Java
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| 20. |
- Nguyen, Björnborg, 1992, et al.
(författare)
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Systematic benchmarking for reproducibility of computer vision algorithms for real-time systems: The example of optic flow estimation
- 2019
-
Ingår i: IEEE International Conference on Intelligent Robots and Systems. - : IEEE. - 2153-0858 .- 2153-0866. ; , s. 5264-5269
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Konferensbidrag (refereegranskat)abstract
- Until now there have been few formalized methods for conducting systematic benchmarking aiming at reproducible results when it comes to computer vision algorithms. This is evident from lists of algorithms submitted to prominent datasets, authors of a novel method in many cases primarily state the performance of their algorithms in relation to a shallow description of the hardware system where it was evaluated. There are significant problems linked to this non-systematic approach of reporting performance, especially when comparing different approaches and when it comes to the reproducibility of claimed results. Furthermore how to conduct retrospective performance analysis such as an algorithm's suitability for embedded real-time systems over time with underlying hardware and software changes in place. This paper proposes and demonstrates a systematic way of addressing such challenges by adopting containerization of software aiming at formalization and reproducibility of benchmarks. Our results show maintainers of broadly accepted datasets in the computer vision community to strive for systematic comparison and reproducibility of submissions to increase the value and adoption of computer vision algorithms in the future.
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| 21. |
- Chatterjee, Bapi, 1982
(författare)
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Efficient Implementation of Concurrent Data Structures on Multi-core and Many-core Architectures
- 2015
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Synchronization of concurrent threads is the central problem in order to design efficient concurrent data-structures. The compute systems widely available in market are increasingly becoming heterogeneous involving multi-core Central Processing Units (CPUs) and many-core Graphics Processing Units (GPUs). This thesis contributes to the research of efficient synchronization in concurrent data-structures in more than one way. It is divided into two parts. In the first part, a novel design of a Set Abstract Data Type (ADT) based on an efficient lock-free Binary Search Tree (BST) with improved amortized bounds of the time complexity of set operations - Add, Remove and Contains, is presented. In the second part, a comprehensive evaluation of concurrent Queue implementations on multi-core CPUs as well as many-core GPUs are presented. Efficient Lock-free BST -To the best of our knowledge, the lock-free BST presented in this thesis is the first to achieve an amortized complexity of O(H(n)+c) for all Set operations where H(n) is the height of a BST on n nodes and c is the contention measure. Also, the presented lock-free algorithm of BST comes with an improved disjoint-access-parallelism compared to the previously existing concurrent BST algorithms. This algorithm uses single-word compare-and-swap (CAS) primitives. The presented algorithm is linearizable. We implemented the algorithm in Java and it shows good scalability. Evaluation of concurrent data-structures - We have evaluated the performance of a number of concurrent FIFO Queue algorithms on multi-core CPUs and many-core GPUs. We studied the portability of existing design of concurrent Queues from CPUs to GPUs which are inherently designed for SIMD programs. We observed that in general concurrent queues offer them to efficient implementation on GPUs with faster cache memory and better performance support for atomic synchronization primitives such as CAS. To the best of our knowledge, this is the first attempt to evaluate a concurrent data-structure on GPUs.
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| 22. |
- Gu, Irene Yu-Hua, 1953, et al.
(författare)
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Grassmann Manifold Online Learning and Partial Occlusion Handling for Visual Object Tracking under Bayesian Formulation
- 2012
-
Ingår i: Proceedings - International Conference on Pattern Recognition. - 1051-4651. - 9784990644109 ; , s. 1463-1466
-
Konferensbidrag (refereegranskat)abstract
- This paper addresses issues of online learning and occlusion handling in video object tracking. Although manifold tracking is promising, large pose changes and long term partial occlusions of video objects remain challenging.We propose a novel manifold tracking scheme that tackles such problems, with the following main novelties: (a) Online estimation of object appearances on Grassmann manifolds; (b) Optimal criterion-based occlusion handling during online learning; (c) Nonlinear dynamic model for appearance basis matrix and its velocity; (b) Bayesian formulations separately for the tracking and the online learning process. Two particle filters are employed: one is on the manifold for generating appearance particles and another on the linear space for generating affine box particles. Tracking and online updating are performed in alternative fashion to mitigate the tracking drift. Experiments on videos have shown robust tracking performance especially when objects contain significantpose changes accompanied with long-term partial occlusions. Evaluations and comparisons with two existing methods provide further support to the proposed method.
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| 23. |
- Bae, Juhee, et al.
(författare)
-
Complex Data Analysis
- 2019
-
Ingår i: Data science in Practice. - Cham : Springer. - 9783319975566 - 9783319975559 ; , s. 157-169
-
Bokkapitel (refereegranskat)abstract
- Data science applications often need to deal with data that does not fit into the standard entity-attribute-value model. In this chapter we discuss three of these other types of data. We discuss texts, images and graphs. The importance of social media is one of the reason for the interest on graphs as they are a way to represent social networks and, in general, any type of interaction between people. In this chapter we present examples of tools that can be used to extract information and, thus, analyze these three types of data. In particular, we discuss topic modeling using a hierarchical statistical model as a way to extract relevant topics from texts, image analysis using convolutional neural networks, and measures and visual methods to summarize information from graphs.
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| 24. |
- Bae, Juhee, et al.
(författare)
-
Visual Data Analysis
- 2019
-
Ingår i: Data science in Practice. - Cham : Springer. - 9783319975566 - 9783319975559 ; , s. 133-155
-
Bokkapitel (refereegranskat)abstract
- Data Science offers a set of powerful approaches for making new discoveries from large and complex data sets. It combines aspects of mathematics, statistics, machine learning, etc. to turn vast amounts of data into new insights and knowledge. However, the sole use of automatic data science techniques for large amounts of complex data limits the human user’s possibilities in the discovery process, since the user is estranged from the process of data exploration. This chapter describes the importance of Information Visualization (InfoVis) and visual analytics (VA) within data science and how interactive visualization can be used to support analysis and decision-making, empowering and complementing data science methods. Moreover, we review perceptual and cognitive aspects, together with design and evaluation methodologies for InfoVis and VA.
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| 25. |
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| 26. |
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| 27. |
- Dodig-Crnkovic, Gordana, 1955
(författare)
-
Significance of models of computation, from Turing model to natural computation
- 2011
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Ingår i: Minds and Machines. - DORDRECHT : Springer Science and Business Media LLC. - 0924-6495 .- 1572-8641. ; 21:2, s. 301-322
-
Tidskriftsartikel (refereegranskat)abstract
- The increased interactivity and connectivity of computational devices along with the spreading of computational tools and computational thinking across the fields, has changed our understanding of the nature of computing. In the course of this development computing models have been extended from the initial abstract symbol manipulating mechanisms of stand-alone, discrete sequential machines, to the models of natural computing in the physical world, generally concurrent asynchronous processes capable of modelling living systems, their informational structures and dynamics on both symbolic and sub-symbolic information processing levels. Present account of models of computation highlights several topics of importance for the development of new understanding of computing and its role: natural computation and the relationship between the model and physical implementation, interactivity as fundamental for computational modelling of concurrent information processing systems such as living organisms and their networks, and the new developments in logic needed to support this generalized framework. Computing understood as information processing is closely related to natural sciences; it helps us recognize connections between sciences, and provides a unified approach for modeling and simulating of both living and non-living systems. © Springer Science+Business Media B.V. 2011.
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| 28. |
- Frezza, S., et al.
(författare)
-
Modelling competencies for computing education beyond 2020 : A research based approach to defining competencies in the computing disciplines
- 2018
-
Ingår i: Annual Conference on Innovation and Technology in Computer Science Education, ITiCSE. - New York, NY, USA : Association for Computing Machinery. - 9781450362238 ; , s. 148-174, s. 148-174
-
Konferensbidrag (refereegranskat)abstract
- How might the content and outcomes of tertiary education programmes be described and analysed in order to understand how they are structured and function? To address this question we develop a framework for modelling graduate competencies linked to tertiary degree programmes in the computing disciplines. While the focus of our work is computing the framework is applicable to education more broadly. The work presented here draws upon the pioneering curricular document for information technology (IT2017), curricular competency frameworks, other related documents such as the software engineering competency model (SWECOM), the Skills Framework for the Information Age (SFIA), current research in competency models, and elicitation workshop results from recent computing conferences. The aim is to inform the ongoing Computing Curricula (CC2020) project, an endeavour supported by the Association for Computing Machinery (ACM) and the IEEE Computer Society. We develop the Competency Learning Framework (CoLeaF), providing an internationally relevant tool for describing competencies. We argue that this competency based approach is well suited for constructing learning environments and assists degree programme architects in dealing with the challenge of developing, describing and including competencies relevant to computer and IT professionals. In this paper we demonstrate how the CoLeaF competency framework can be applied in practice, and though a series of case studies demonstrate its effectiveness and analytical power as a tool for describing and comparing degree programmes in the international higher education landscape.
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| 29. |
- Mitra, Karan, et al.
(författare)
-
ALPINE : A Bayesian System For Cloud Performance Diagnosis And Prediction
- 2017
-
Ingår i: 2017 IEEE International Conference on Services Computing (SCC). - Piscataway, NJ : IEEE. - 9781538620052 ; , s. 281-288
-
Konferensbidrag (refereegranskat)abstract
- Cloud performance diagnosis and prediction is a challenging problem due to the stochastic nature of the cloud systems. Cloud performance is affected by a large set of factors such as virtual machine types, regions, workloads, wide area network delay and bandwidth. Therefore, necessitating the determination of complex relationships between these factors. The current research in this area does not address the challenge of modeling the uncertain and complex relationships between these factors. Further, the challenge of cloud performance prediction under uncertainty has not garnered sufficient attention. This paper proposes, develops and validates ALPINE, a Bayesian system for cloud performance diagnosis and prediction. ALPINE incorporates Bayesian networks to model uncertain and complex relationships between several factors mentioned above. It handles missing, scarce and sparse data to diagnose and predict stochastic cloud performance efficiently. We validate our proposed system using extensive real data and show that it predicts cloud performance with high accuracy of 91.93%.
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| 30. |
- Torra, Vicenç, et al.
(författare)
-
Data privacy
- 2019
-
Ingår i: Data science in Practice. - Cham : Springer. - 9783319975566 - 9783319975559 ; , s. 121-132
-
Bokkapitel (refereegranskat)abstract
- In this chapter we present an overview of the topic data privacy. We review privacy models and measures of disclosure risk. These models and measures provide computational definitions of what privacy means, and of how to evaluate the privacy level of a data set. Then, we give a summary of data protection mechanisms. We provide a classification of these methods according to three dimensions: whose privacy is being sought, the computations to be done, and the number of data sources. Finally, we describe masking methods. Such methods are the data protection mechanisms used for databases when the data use is undefined and the protected database is required to be useful for several data uses. We also provide a definition of information loss (or data utility) for this type of data protection mechanism. The chapter finishes with a summary.
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| 31. |
- Tossou, Aristide, 1989
(författare)
-
Privacy in the Age of Artificial Intelligence
- 2017
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An increasing number of people are using the Internet in their daily life. Indeed, more than 40% of the world population have access to the Internet, while Facebook (one of the top social network on the web) is actively used by more than 1.3 billion users each day (Statista 2017). This huge amount of customers creates an abundance of user data containing personal information. These data are becoming valuable to companies and used in various way to enrich user experience or increase revenue. This has led many citizens and politicians to be concerned about their privacy on the Internet to such an extent that the European Union issued a "Right to be Forgotten" ruling, reflecting the desire of many individuals to restrict the use of their information. As a result, many online companies pledged to collect or share user data anonymously. However, anonymisation is not enough and makes no sense in many cases. For example, an MIT graduate was able to easily re-identify the private medical data of Governor William Weld of Massachusetts from supposedly anonymous records released by the Group Insurance Commission. All she did was to link the insurance data with the publicly available voter registration list and some background knowledge (Ohm 2009). Those shortcomings have led to the development of a more rigorous mathematical framework for privacy: Differential privacy. Its main characteristic is to bound the information one can gain from released data, no matter what side information they have available. In this thesis, we present differentially private algorithms for the multi-armed bandit problem. This is a well known multi round game, that originally stemmed from clinical trials applications and is now one promising solution to enrich user experience in the booming online advertising and recommendation systems. However, as recommendation systems are inherently based on user data, there is always some private information leakage. In our work, we show how to minimise this privacy loss, while maintaining the effectiveness of such algorithms. In addition, we show how one can take advantage of the correlation structure inherent in a user graph such as the one arising from a social network.
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| 32. |
- Paçacı, Görkem, et al.
(författare)
-
Towards a visual compositional relational programming methodology
- 2012
-
Ingår i: Diagrams 2012. ; , s. 17-19
-
Konferensbidrag (refereegranskat)abstract
- We present a new visual programming method, based on Combilog, a compositional relational programming language. In this paper we focus on the compositional aspect of Combilog, the make operator, visually implementing it via a modification of Higraph diagrams, in an attempt to overcome the obscurity and complexity in the textual representation of this operator.
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| 33. |
- Ge, Chenjie, 1991, et al.
(författare)
-
Co-Saliency-Enhanced Deep Recurrent Convolutional Networks for Human Fall Detection in E-Healthcare
- 2018
-
Ingår i: Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS. - 1557-170X. ; , s. 1572-1575
-
Konferensbidrag (refereegranskat)abstract
- This paper addresses the issue of fall detection from videos for e-healthcare and assisted-living. Instead of using conventional hand-crafted features from videos, we propose a fall detection scheme based on co-saliency-enhanced recurrent convolutional network (RCN) architecture for fall detection from videos. In the proposed scheme, a deep learning method RCN is realized by a set of Convolutional Neural Networks (CNNs) in segment-levels followed by a Recurrent Neural Network (RNN), Long Short-Term Memory (LSTM), to handle the time-dependent video frames. The co-saliency-based method enhances salient human activity regions hence further improves the deep learning performance. The main contributions of the paper include: (a) propose a recurrent convolutional network (RCN) architecture that is dedicated to the tasks of human fall detection in videos; (b) integrate a co-saliency enhancement to the deep learning scheme for further improving the deep learning performance; (c) extensive empirical tests for performance analysis and evaluation under different network settings and data partitioning. Experiments using the proposed scheme were conducted on an open dataset containing multicamera videos from different view angles, results have shown very good performance (test accuracy 98.96%). Comparisons with two existing methods have provided further support to the proposed scheme.
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| 34. |
- Höglund, Lars, 1946, et al.
(författare)
-
Maskininlärningsbaserad indexering av digitaliserade museiartefakter - projektrapport
- 2012
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Projektet har genomfört försök med maskinbaserad analys och maskininlärning för automatisk indexering och analys av bilder som stöd för registrering av föremål i museibestånd. Resultaten visar att detta är möjligt för avgränsade delmängder i kombination med maskininlärning som stöd för, men inte som ersättning för, manuell analys. Projektet har också funnit behov av utveckling av ett användargränssnitt för både text och bildsökning och utvecklat en prototyplösning för detta, vilket finns dokumenterat i denna rapport och i ett separat appendix till rapporten. Materialet utgör grundunderlag för implementeringar som innebär utökade sökmöjligheter, effektivare registrering samt ett användarvänligt gränssnitt. Arbetet ligger i framkant av forskningsområdets resultat och etablerade metoder och kombinerar statististiska, lingvistiska och datavetenskapliga metoder. Se länk till rapport och även länk till appendix längre ned.
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| 35. |
- Menghi, Claudio, 1987, et al.
(författare)
-
Poster: Property specification patterns for robotic missions
- 2018
-
Ingår i: Proceedings - International Conference on Software Engineering. - New York, NY, USA : ACM. - 0270-5257. ; Part F137351, s. 434-435
-
Konferensbidrag (refereegranskat)abstract
- Engineering dependable software for mobile robots is becoming increasingly important. A core asset in engineering mobile robots is the mission specification-A formal description of the goals that mobile robots shall achieve. Such mission specifications are used, among others, to synthesize, verify, simulate, or guide the engineering of robot software. Development of precise mission specifications is challenging. Engineers need to translate the mission requirements into specification structures expressed in a logical language-A laborious and error-prone task. To mitigate this problem, we present a catalog of mission specification patterns for mobile robots. Our focus is on robot movement, one of the most prominent and recurrent specification problems for mobile robots. Our catalog maps common mission specification problems to recurrent solutions, which we provide as templates that can be used by engineers. The patterns are the result of analyzing missions extracted from the literature. For each pattern, we describe usage intent, known uses, relationships to other patterns, and-most importantly-A template representing the solution as a logical formula in temporal logic. Our specification patterns constitute reusable building blocks that can be used by engineers to create complex mission specifications while reducing specification mistakes. We believe that our patterns support researchers working on tool support and techniques to synthesize and verify mission specifications, and language designers creating rich domain-specific languages for mobile robots, incorporating our patterns as language concepts.
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| 36. |
- Alahdab, Mohannad, et al.
(författare)
-
Empirical Analysis of Hidden Technical Debt Patterns in Machine Learning Software
- 2019
-
Ingår i: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). - Cham : Springer International Publishing. - 1611-3349 .- 0302-9743. ; 11915 LNCS, s. 195-202
-
Konferensbidrag (refereegranskat)abstract
- Context/Background Machine Learning (ML) software has special ability for increasing technical debt due to ML-specific issues besides having all the problems of regular code. The term “Hidden Technical Debt” (HTD) was coined by Sculley et al. to address maintainability issues in ML software as an analogy to technical debt in traditional software. Goal The aim of this paper is to empirically analyse how HTD patterns emerge during the early development phase of ML software, namely the prototyping phase. Method Therefore, we conducted a case study with subject systems as ML models planned to be integrated into the software system owned by Västtrafik, the public transportation agency in the west area of Sweden. Results During our case study, we could detect HTD patterns, which have the potential to emerge in ML prototypes, except for “Legacy Features”, “Correlated features”, and “Plain Old Data Type Smell”. Conclusion Preliminary results indicate that emergence of significant amount of HTD patterns can occur during prototyping phase. However, generalizability of our results require analyses of further ML systems from various domains.
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| 37. |
- Andersson, Niclas S, 1971, et al.
(författare)
-
Feature-Based Response Classification in Nonlinear Structural Design Simulations
- 2018
-
Ingår i: SAE International Journal of Vehicle Dynamics, Stability, and NVH. - : SAE International. - 2380-2162 .- 2380-2170. ; 2:3, s. 185-202
-
Tidskriftsartikel (refereegranskat)abstract
- An applied system design analysis approach for automated processing and classification of simulated structural responses is presented. Deterministic and nonlinear dynamics are studied under ideal loading and low noise conditions to determine fundamental system properties, how they vary and possibly interact. Using powerful computer resources, large amounts of simulated raw data can be produced in a short period of time. Efficient tools for data processing and interpretation are then needed, but existing ones often require much manual preparation and direct human judgement. Thus, there is a need to develop techniques that help to treat more virtual prototype variants and efficiently extract useful information from them. For this, time signals are evaluated by methods commonly used within structural dynamics and statistical learning. A multi-level multi-frequency stimulus function is constructed and simulated response signals are combined into frequency domain functions. These are associated with qualitative system features, such as being periodic or aperiodic, linear or nonlinear and further into subcategories of nonlinear systems, such as fundamental, sub or super harmonic and even or odd order types. Appropriate classes are then determined from selected feature metrics and rules-of-thumb criteria. To automate the classification of large data sets, a support vector machine is trained on categorised responses to determine whether a single feature, or combinations of features, applies or not. The trained classifier can then efficiently process new sets of data and pick out cases that are associated with possible vibrational problems, which subsequently can be further analysed and understood. This article describes elements of the analysis, discuss the effectiveness of evaluated feature metrics, reports practical considerations and results from two separate training study examples.
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| 38. |
- Atalar, Aras, 1985
(författare)
-
Throughput and energy efficiency of lock-free data structures: Execution Models and Analyses
- 2018
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Concurrent data structures are key program components to harness the available parallelism in multi-core processors. Lock-free algorithmic implementations of concurrent data structures offer high scalability and possess desirable properties such as immunity to deadlocks, convoying and priority inversion. In this thesis, we develop analytical tools to model and analyze the throughput and energy consumption of concurrent lock-free data structures. We start our study with a general class of lock-free data structures. Then, we target more specialized designs for lock-free queues. Finally, we focus on the search data structures that possess different characteristics compared to previously mentioned data structures. Performance of lock-free data structures: This thesis contributes to the problem of making ends meet between theoretical bounds and actual measured throughput. As the first step, we consider a general class of lock-free data structures and propose three analytical frameworks with different flavors. Analyses of this class also cover efficient implementations of a set of fundamental data structures that suffer from inherent sequential bottlenecks. We model the executions and examine the impact of contention on the throughput of these algorithms. Our analyses lead to optimization methods on memory management and back-off strategies. Performance and energy efficiency of lock-free queues: We take a step further to model the throughput of lock-free operations and their interaction. Considering shared queues, as a key paradigm for data sharing, operations (En- queue, Dequeue) access the opposite ends of a queue. Same type of operations might contend with each other on a non-empty queue. However, all types of operations are subject to interaction when the queue is empty. We first decorrelate the throughput of dequeuers’ and enqueuers’ into several uncorrelated basic throughputs, and reconstruct the main throughputs as a function of these basic throughputs. Besides, we model the power dissipation and integrate it with the throughput estimations to extract the energy consumption of applications that utilize lock-free queues. Performance of lock-free search data structures: Lock-free designs that utilize fine-grained synchronization have produced efficient implementations of search data structures. These designs reveal different characteristics compared to the previous set of lock-free data structures with inherent sequential bottlenecks. We introduce a new way of modeling and analyzing the throughput of search data structures under stationary and memoryless access patterns..
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| 39. |
- Bernhard, David, et al.
(författare)
-
Security proofs for Participation privacy, receipt-freeness and ballot privacy for the helios voting scheme
- 2017
-
Ingår i: ARES '17 Proceedings of the 12th International Conference on Availability, Reliability and Security. - New York : Association for Computing Machinery (ACM). - 9781450352574
-
Konferensbidrag (refereegranskat)abstract
- The Helios voting scheme is well studied including formal proofs for verifiability and ballot privacy. However, depending on its version, the scheme provides either participation privacy (hiding who participated in the election) or verifiability against malicious bulletin board (preventing election manipulation by ballot stuffing), but not both at the same time. It also does not provide receipt-freeness, thus enabling vote buying by letting the voters construct receipts proving how they voted. Recently, an extension to Helios, further referred to as KTV-Helios, has been proposed that claims to provide these additional security properties. However, the authors of KTV-Helios did not prove their claims. Our contribution is to provide formal definitions for participation privacy and receipt-freeness that we applied to KTV-Helios. In order to evaluate the fulfillment of participation privacy and receipt-freeness, we furthermore applied the existing definition of ballot privacy, which was also used for evaluating the security of Helios, in order to show that ballot privacy also holds for KTV-Helios
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| 40. |
- Bonneau, Charlotte, et al.
(författare)
-
Deconstruction of Crystalline Networks into Underlying Nets: Relevance for Terminology Guidelines and Crystallographic Databases
- 2018
-
Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7505 .- 1528-7483. ; 18:6, s. 3411-3418
-
Tidskriftsartikel (refereegranskat)abstract
- This communication briefly reviews why network topology is an important tool (for understanding, comparing, communicating, designing, and solving crystal structures from powder diffraction data) and then discusses the terms of an IUPAC project dealing with various aspects of network topology. One is the ambiguity in node assignment, and this question is addressed in more detail. First, we define the most important approaches: the "all node" deconstruction considering all branch points of the linkers, the "single node" deconstruction considering only components mixed, and the ToposPro "standard representation" also considering linkers as one node but, if present, takes each metal atom as a separate node. These methods are applied to a number of metal-organic framework structures (MOFs, although this is just one example of materials this method is applicable on), and it is concluded that the "all node" method potentially yields more information on the structure in question but cannot be recommended as the only way of reporting the network topology. In addition, several terms needing definitions are discussed.
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| 41. |
- Brunetta, Carlo, 1992
(författare)
-
Cryptographic Tools for Privacy Preservation and Verifiable Randomness
- 2018
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Our society revolves around communication. The Internet is the biggest, cheapest and fastest digital communication channel used nowadays. Due to the continuous increase of daily communication among people worldwide, more and more data might be stolen, misused or tampered. We require to protect our communications and data by achieving privacy and confidentiality. Despite the two terms, "privacy" and "confidentiality",are often used as synonymous, in cryptography they are modelled in very different ways. Intuitively, cryptography can be seen as a tool-box in which every scheme, protocol or primitive is a tool that can be used to solve specific problems and provide specific communication security guarantees such as confidentiality. Privacy is instead not easy to describe and capture since it often depends on "which" information is available, "how" are these data used and/or "who" has access to our data. This licentiate thesis raises research questions and proposes solutions related to: the possibility of defining encryption schemes that provide both strong security and privacy guarantees; the importance of designing cryptographic protocols that are compliant with real-life privacy-laws or regulations; and the necessity of defining a post-quantum mechanism to achieve the verifiability of randomness. In more details, the thesis achievements are: (a) defining a new class of encryption schemes, by weakening the correctness property, that achieves Differential Privacy (DP), i.e., a mathematically sound definition of privacy; (b) formalizing a security model for a subset of articles in the European General Data Protection Regulation (GDPR), designing and implementing a cryptographic protocol based on the proposed GDPR-oriented security model, and; (c) proposing a methodology to compile a post-quantum interactive protocol for proving the correct computation of a pseudorandom function into a non-interactive one, yielding a post-quantum mechanism for verifiable randomness.
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| 42. |
- Camilleri, John J., 1986, et al.
(författare)
-
Modelling and analysis of normative documents
- 2017
-
Ingår i: Journal of Logical and Algebraic Methods in Programming. - : Elsevier BV. - 2352-2208 .- 2352-2216. ; 91, s. 33-59
-
Tidskriftsartikel (refereegranskat)abstract
- We are interested in using formal methods to analyse normative documents or contracts such as terms of use, privacy policies, and service agreements. We begin by modelling such documents in terms of obligations, permissions and prohibitions of agents over actions, restricted by timing constraints and including potential penalties resulting from the non-fulfilment of clauses. This is done using the C-O Diagram formalism, which we have extended syntactically and for which we have defined a new trace semantics. Models in this formalism can then be translated into networks of timed automata, and we have a complete working implementation of this translation. The network of automata is used as a specification of a normative document, making it amenable to verification against given properties. By applying this approach to a case study from a real-world contract, we show the kinds of analysis possible through both syntactic querying on the structure of the model, as well as verification of properties using UPPAAL.
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| 43. |
- Dolonius, Dan, 1985
(författare)
-
Sparse Voxel DAGs for Shadows and for Geometry with Colors
- 2018
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Triangles are probably the most common format for shapes in computer graphics. Nevertheless, when high detail is desired, Sparse Voxel Octrees (SVO) and Sparse Voxel Directed Acyclic Graphs (DAG) can be considerably more memory efficient. One of the first practical use cases for DAGs was to use the structure to represent precomputed shadows. However, previous methods were very time consuming in building the DAG and did not support any other attributes than discretized geometry. Furthermore, when used for scene object representation, the DAGs lacked proper support for properties such as object colors. The focus on this thesis is to speed up the build times of the DAG and to allow other, important, attributes such as colors to be encoded. This thesis is a collection of three papers where we in Paper I solve the problem with slow construction times while also further compressing the DAG, allowing much faster feedback to an artist making changes to a scene and also opening up the possibility to recompute the DAG in run time for slowly moving shadows. If a unique color per voxel is desired, which uncompressed would require 3 bytes per voxel, we realize that the benefit from compressing the geometry (down to or even below one bit per voxel) is rendered practically useless. We thus need to find a way to compress the colors as well. In Paper IIA, we solve this issue by mapping the voxel colors to a texture, allowing for the use of conventional compression algorithms, as well as a novel format designed for real-time performance. In Paper IIB, we further significantly improve the compression.
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| 44. |
- Ebadi Tavallaei, Hamid, 1987, et al.
(författare)
-
Sampling and Partitioning for Differential Privacy
- 2016
-
Ingår i: Privacy Security & Trust Conference 2016. - 9781509043798 ; , s. 664-673
-
Konferensbidrag (refereegranskat)abstract
- Differential privacy enjoys increasing popularity thanks to both a precise semantics for privacy and effective enforcement mechanisms. Many tools have been proposed to spread its use and ease the task of the concerned data scientist. The most promising among them completely discharge the user of the privacy concerns by transparently taking care of the privacy budget. However, their implementation proves to be delicate, and introduce flaws by falsifying some of the theoretical assumptions made to guarantee differential privacy. Moreover, such tools rely on assumptions leading to over-approximations which artificially reduce utility. In this paper we focus on a key mechanism that tools do not support well: sampling. We demonstrate an attack on PINQ (McSherry, SIGMOD 2009), one of these tools, relying on the difference between its internal mechanics and the formal theory for the sampling operation, and study a range of sampling methods and show how they can be correctly implemented in a system for differential privacy.
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| 45. |
- Gerdes, Alex, 1978, et al.
(författare)
-
Understanding formal specifications through good examples
- 2018
-
Ingår i: Erlang 2018 - Proceedings of the 17th ACM SIGPLAN International Workshop on Erlang, co-located with ICFP 2018. - New York, NY, USA : ACM. ; , s. 13-24
-
Konferensbidrag (refereegranskat)abstract
- Formal specifications of software applications are hard to understand, even for domain experts. Because a formal specification is abstract, reading it does not immediately convey the expected behaviour of the software. Carefully chosen examples of the software’s behaviour, on the other hand, are concrete and easy to understand—but poorly-chosen examples are more confusing than helpful. In order to understand formal specifications, software developers need good examples. We have created a method that automatically derives a suite of good examples from a formal specification. Each example is judged by our method to illustrate one feature of the specification. The generated examples give users a good understanding of the behaviour of the software. We evaluated our method by measuring how well students understood an API when given different sets of examples; the students given our examples showed significantly better understanding.
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| 46. |
- Hovey, Gary, 1955, et al.
(författare)
-
A framework for RFI simulation and performance verification
- 2019
-
Ingår i: RFI 2019 - Proceedings of 2019 Radio Frequency Interference: Coexisting with Radio Frequency Interference.
-
Konferensbidrag (refereegranskat)abstract
- Modern radio telescopes, like the proposed Square Kilometre Array (SKA), are extremely sensitive and the faint signals they receive can easily be contaminated irreversibly by stray radio frequency interference (RFI). Understanding how radio telescope performance is degraded by RFI is important. In this paper we describe an RFI simulation framework that can be used to generate test stimulus and verify a telescope's performance. The framework can be used during design to investigate the impact of various RFI scenarios and develop mitigation strategies. As well, it can be used to exercise and test hardware firmware after a system is installed. A prototype of the framework was implemented in the Python computer language to demonstrate the key concepts. Additionally, we outline the framework requirements, describe a suitable software structure and discuss a prototype implementation. As well, we present measurements made to verify the software generates correct test stimulus, for RFI from aircraft distance measuring equipment (DME). The work described was carried out to evaluate the impact of RFI on the Square Kilometre Array, an international effort to build the largest most sensitive radio telescope.
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| 47. |
- John, Stefan, et al.
(författare)
-
Searching for optimal models: Comparing two encoding approaches
- 2019
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Ingår i: Journal of Object Technology. - : AITO - Association Internationale pour les Technologies Objets. - 1660-1769. ; 18:3, s. 1-22
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Tidskriftsartikel (refereegranskat)abstract
- Search-Based Software Engineering (SBSE) is about solving software development problems by formulating them as optimization problems. In the last years, combining SBSE and Model-Driven Engineering (MDE), where models and model transformations are treated as key artifacts in the development of complex systems, has become increasingly popular. While search-based techniques have often successfully been applied to tackle MDE problems, a recent line of research investigates how a model-driven design can make optimization more easily accessible to a wider audience. In previous model-driven optimization efforts, a major design decision concerns the way in which solutions are encoded. Two main options have been explored: a model-based encoding representing candidate solutions as models, and a rule-based encoding representing them as sequences of transformation rule applications. While both encodings have been applied to different use cases, no study has yet compared them systematically. To close this gap, we evaluate both approaches on a common set of optimization problems, investigating their impact on the optimization performance. Additionally, we discuss their differences, strengths, and weaknesses laying the foundation for a knowledgeable choice of the right encoding for the right problem.
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| 48. |
- Jönsson, Daniel
(författare)
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Enhancing Salient Features in Volumetric Data Using Illumination and Transfer Functions
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The visualization of volume data is a fundamental component in the medical domain. Volume data is used in the clinical work-flow to diagnose patients and is therefore of uttermost importance. The amount of data is rapidly increasing as sensors, such as computed tomography scanners, become capable of measuring more details and gathering more data over time. Unfortunately, the increasing amount of data makes it computationally challenging to interactively apply high quality methods to increase shape and depth perception. Furthermore, methods for exploring volume data has mostly been designed for experts, which prohibits novice users from exploring volume data. This thesis aims to address these challenges by introducing efficient methods for enhancing salient features through high quality illumination as well as methods for intuitive volume data exploration.Humans are interpreting the world around them by observing how light interacts with objects. Shadows enable us to better determine distances while shifts in color enable us to better distinguish objects and identify their shape. These concepts are also applicable to computer generated content. The perception in volume data visualization can therefore be improved by simulating real-world light interaction. This thesis presents efficient methods that are capable of interactively simulating realistic light propagation in volume data. In particular, this work shows how a multi-resolution grid can be used to encode the attenuation of light from all directions using spherical harmonics and thereby enable advanced interactive dynamic light configurations. Two methods are also presented that allow photon mapping calculations to be focused on visually changing areas.The results demonstrate that photon mapping can be used in interactive volume visualization for both static and time-varying volume data.Efficient and intuitive exploration of volume data requires methods that are easy to use and reflect the objects that were measured. A value that has been collected by a sensor commonly represents the material existing within a small neighborhood around a location. Recreating the original materials is difficult since the value represents a mixture of them. This is referred to as the partial-volume problem. A method is presented that derives knowledge from the user in order to reconstruct the original materials in a way which is more in line with what the user would expect. Sharp boundaries are visualized where the certainty is high while uncertain areas are visualized with fuzzy boundaries. The volume exploration process of mapping data values to optical properties through the transfer function has traditionally been complex and performed by expert users. A study at a science center showed that visitors favor the presented dynamic gallery method compared to the most commonly used transfer function editor.
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| 49. |
- Koniaris, Christos, 1979-
(författare)
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Perceptually motivated speech recognition and mispronunciation detection
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This doctoral thesis is the result of a research effort performed in two fields of speech technology, i.e., speech recognition and mispronunciation detection. Although the two areas are clearly distinguishable, the proposed approaches share a common hypothesis based on psychoacoustic processing of speech signals. The conjecture implies that the human auditory periphery provides a relatively good separation of different sound classes. Hence, it is possible to use recent findings from psychoacoustic perception together with mathematical and computational tools to model the auditory sensitivities to small speech signal changes.The performance of an automatic speech recognition system strongly depends on the representation used for the front-end. If the extracted features do not include all relevant information, the performance of the classification stage is inherently suboptimal. The work described in Papers A, B and C is motivated by the fact that humans perform better at speech recognition than machines, particularly for noisy environments. The goal is to make use of knowledge of human perception in the selection and optimization of speech features for speech recognition. These papers show that maximizing the similarity of the Euclidean geometry of the features to the geometry of the perceptual domain is a powerful tool to select or optimize features. Experiments with a practical speech recognizer confirm the validity of the principle. It is also shown an approach to improve mel frequency cepstrum coefficients (MFCCs) through offline optimization. The method has three advantages: i) it is computationally inexpensive, ii) it does not use the auditory model directly, thus avoiding its computational cost, and iii) importantly, it provides better recognition performance than traditional MFCCs for both clean and noisy conditions.The second task concerns automatic pronunciation error detection. The research, described in Papers D, E and F, is motivated by the observation that almost all native speakers perceive, relatively easily, the acoustic characteristics of their own language when it is produced by speakers of the language. Small variations within a phoneme category, sometimes different for various phonemes, do not change significantly the perception of the language’s own sounds. Several methods are introduced based on similarity measures of the Euclidean space spanned by the acoustic representations of the speech signal and the Euclidean space spanned by an auditory model output, to identify the problematic phonemes for a given speaker. The methods are tested for groups of speakers from different languages and evaluated according to a theoretical linguistic study showing that they can capture many of the problematic phonemes that speakers from each language mispronounce. Finally, a listening test on the same dataset verifies the validity of these methods.
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| 50. |
- Lenhard, Jörg, et al.
(författare)
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Lessons Learned from Evaluating Workflow Management Systems
- 2018
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Ingår i: Service-Oriented Computing – ICSOC 2017 Workshops. - Cham : Springer. - 9783319917634 - 9783319917641 ; , s. 216-228
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Konferensbidrag (refereegranskat)abstract
- Work ow Management Systems (WfMSs) today act as ser- vice composition engines and service-oriented middleware to enable the execution of automated business processes. Automation based on WfMSs promises to enable the model-driven construction of exible and easily maintainable services with high-performance characteristics. In the past decade, signi cant e ort has been invested into standardizing WfMSs that compose services, with standards such as the Web Services Business Process Execution Language (WS-BPEL) or the Business Process Model and Notation (BPMN). One of the aims of standardization is to enable users of WfMSs to compare di erent systems and to avoid vendor lock-in. Despite these e orts, there are many expectations concerning portabil- ity, performance e ciency, usability, reliability and maintainability of WfMSs that are likely to be unful lled. In this work, we synthesize the ndings of two research initiatives that deal with WfMSs conformance and performance benchmarking to distill a set of lessons learned and best practices. These ndings provide useful advice for practitioners who plan to evaluate and use WfMSs and for WfMS vendors that would like to foster wider adoption of process-centric service composition middleware.
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