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  • 1. Abel, Olubunmi
    et al.
    Shatunov, Aleksey
    Jones, Ashley R.
    Andersen, Peter M.
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Neurologi.
    Powell, John F.
    Al-Chalabi, Ammar
    Development of a Smartphone App for a Genetics Website: The Amyotrophic Lateral Sclerosis Online Genetics Database (ALSoD)2013Ingår i: JMIR mhealth and uhealth, E-ISSN 2291-5222, Vol. 1, nr 2, artikel-id e18Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: The ALS Online Genetics Database (ALSoD) website holds mutation, geographical, and phenotype data on genes implicated in amyotrophic lateral sclerosis (ALS) and links to bioinformatics resources, publications, and tools for analysis. On average, there are 300 unique visits per day, suggesting a high demand from the research community. To enable wider access, we developed a mobile-friendly version of the website and a smartphone app. Objective: We sought to compare data traffic before and after implementation of a mobile version of the website to assess utility. Methods: We identified the most frequently viewed pages using Google Analytics and our in-house analytic monitoring. For these, we optimized the content layout of the screen, reduced image sizes, and summarized available information. We used the Microsoft. NET framework mobile detection property (HttpRequest. IsMobileDevice in the Request. Browser object in conjunction with HttpRequest. UserAgent), which returns a true value if the browser is a recognized mobile device. For app development, we used the Eclipse integrated development environment with Android plug-ins. We wrapped the mobile website version with the WebView object in Android. Simulators were downloaded to test and debug the applications. Results: The website automatically detects access from a mobile phone and redirects pages to fit the smaller screen. Because the amount of data stored on ALSoD is very large, the available information for display using smartphone access is deliberately restricted to improve usability. Visits to the website increased from 2231 to 2820, yielding a 26% increase from the pre-mobile to post-mobile period and an increase from 103 to 340 visits (230%) using mobile devices (including tablets). The smartphone app is currently available on BlackBerry and Android devices and will be available shortly on iOS as well. Conclusions: Further development of the ALSoD website has allowed access through smartphones and tablets, either through the website or directly through a mobile app, making genetic data stored on the database readily accessible to researchers and patients across multiple devices.

  • 2.
    Addi, Ait-Mlouk
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Tarik, Agouti
    Cadi Ayyad university.
    DM-MCDA: A web-based platform for data mining and multiple criteria decision analysis: A case study on road accident2019Ingår i: SoftwareX, E-ISSN 2352-7110, Vol. 10, artikel-id 100323Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Today’s ultra-connected world is generating a huge amount of data stored in databases and cloud environment especially in the era of transportation. These databases need to be processed and analyzed to extract useful information and present it as a valid element for transportation managers for further use, such as road safety, shipping delays, and shipping optimization. The potential of data mining algorithms is largely untapped, this paper shows large-scale techniques such as associations rule analysis, multiple criteria analysis, and time series to improve road safety by identifying hot-spots in advance and giving chance to drivers to avoid the dangers. Indeed, we proposed a framework DM-MCDA based on association rules mining as a preliminary task to extract relationships between variables related to a road accident, and then integrate multiple criteria analysis to help decision-makers to make their choice of the most relevant rules. The developed system is flexible and allows intuitive creation and execution of different algorithms for an extensive range of road traffic topics. DM-MCDA can be expanded with new topics on demand, rendering knowledge extraction more robust and provide meaningful information that could help in developing suitable policies for decision-makers.

  • 3.
    Ali-Eldin, Ahmed
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Capacity Scaling for Elastic Compute Clouds2013Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    AbstractCloud computing is a computing model that allows better management, higher utiliza-tion and reduced operating costs for datacenters while providing on demand resourceprovisioning for different customers. Data centers are often enormous in size andcomplexity. In order to fully realize the cloud computing model, efficient cloud man-agement software systems that can deal with the datacenter size and complexity needto be designed and built.This thesis studies automated cloud elasticity management, one of the main andcrucial datacenter management capabilities. Elasticity can be defined as the abilityof cloud infrastructures to rapidly change the amount of resources allocated to anapplication in the cloud according to its demand. This work introduces algorithms,techniques and tools that a cloud provider can use to automate dynamic resource pro-visioning allowing the provider to better manage the datacenter resources. We designtwo automated elasticity algorithms for cloud infrastructures that predict the futureload for an application running on the cloud. It is assumed that a request is either ser-viced or dropped after one time unit, that all requests are homogeneous and that it takesone time unit to add or remove resources. We discuss the different design approachesfor elasticity controllers and evaluate our algorithms using real workload traces. Wecompare the performance of our algorithms with a state-of-the-art controller. We ex-tend on the design of the best performing controller out of our two controllers anddrop the assumptions made during the first design. The controller is evaluated with aset of different real workloads.All controllers are designed using certain assumptions on the underlying systemmodel and operating conditions. This limits a controller’s performance if the modelor operating conditions change. With this as a starting point, we design a workloadanalysis and classification tool that assigns a workload to its most suitable elasticitycontroller out of a set of implemented controllers. The tool has two main components,an analyzer and a classifier. The analyzer analyzes a workload and feeds the analysisresults to the classifier. The classifier assigns a workload to the most suitable elasticitycontroller based on the workload characteristics and a set of predefined business levelobjectives. The tool is evaluated with a set of collected real workloads and a set ofgenerated synthetic workloads. Our evaluation results shows that the tool can help acloud provider to improve the QoS provided to the customers.

  • 4.
    Ali-Eldin, Ahmed
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    El-Ansary, Sameh
    Nile University.
    Optimizing Replica Placement in Peer-Assisted Cloud Stores2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Peer-assisted cloud storage systems use the unutilizedresources of the clients subscribed to a storage cloudto offload the servers of the cloud. The provider distributesdata replicas on the clients instead of replicating on the localinfrastructure. These replicas allow the provider to providea highly available, reliable and cheap service at a reducedcost. In this work we introduce NileStore, a protocol forreplication management in peer-assisted cloud storage. Theprotocol converts the replica placement problem into a lineartask assignment problem. We design five utility functionsto optimize placement taking into account the bandwidth,free storage and the size of data in need of replication oneach peer. The problem is solved using a suboptimal greedyoptimization algorithm. We show our simulation results usingthe different utilities under realistic network conditions. Ourresults show that using our approach offloads the cloud serversby about 90% compared to a random placement algorithmwhile consuming 98.5% less resources compared to a normalstorage cloud.

  • 5.
    Ali-Eldin, Ahmed
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    El-Ansary, Sameh
    Nile University.
    Replica Placement in Peer-Assisted Clouds: An Economic Approach2011Ingår i: Lecture Notes in Computer Science / [ed] Pascal Felber, Romain Rouvoy, Springer, 2011, s. 208-213Konferensbidrag (Refereegranskat)
    Abstract [en]

    We introduce NileStore, a replica placement algorithm based on an economical model for use in Peer-assisted cloud storage. The algorithm uses storage and bandwidth resources of peers to offload the cloud provider’s resources. We formulate the placement problem as a linear task assignment problem where the aim is to minimize time needed for file replicas to reach a certain desired threshold. Using simulation, We reduce the probability of a file being served from the provider’s servers by more than 97.5% under realistic network conditions.

  • 6.
    Ali-Eldin, Ahmed
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Ilyushkin, Alexey
    Ghit, Bogdan
    Herbst, Nikolas Roman
    Papadopoulos, Alessandro
    Losup, Alexandru
    Which Cloud Auto-Scaler Should I Use for my Application?: Benchmarking Auto-Scaling Algorithms2016Ingår i: PROCEEDINGS OF THE 2016 ACM/SPEC INTERNATIONAL CONFERENCE ON PERFORMANCE ENGINEERING (ICPE'16), Association for Computing Machinery (ACM), 2016, s. 131-132Konferensbidrag (Refereegranskat)
  • 7.
    Ali-Eldin, Ahmed
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kihl, Maria
    Lund University.
    Tordsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Analysis and characterization of a Video-on-Demand service workload2015Ingår i: Proceedings of the 6th ACM Multimedia Systems Conference, MMSys 2015, ACM Digital Library, 2015, s. 189-200Konferensbidrag (Refereegranskat)
    Abstract [en]

    Video-on-Demand (VoD) and video sharing services accountfor a large percentage of the total downstream Internet traf-fic. In order to provide a better understanding of the loadon these services, we analyze and model a workload tracefrom a VoD service provided by a major Swedish TV broad-caster. The trace contains over half a million requests gener-ated by more than 20000 unique users. Among other things,we study the request arrival rate, the inter-arrival time, thespikes in the workload, the video popularity distribution, thestreaming bit-rate distribution and the video duration distri-bution. Our results show that the user and the session ar-rival rates for the TV4 workload does not follow a Poissonprocess. The arrival rate distribution is modeled using a log-normal distribution while the inter-arrival time distributionis modeled using a stretched exponential distribution. Weobserve the “impatient user” behavior where users abandonstreaming sessions after minutes or even seconds of startingthem. Both very popular videos and non-popular videos areparticularly affected by impatient users. We investigate ifthis behavior is an invariant for VoD workloads.

  • 8.
    Ali-Eldin, Ahmed
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Rezaie, Ali
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Mehta, Amardeep
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Razroev, Stanislav
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Sjöstedt-de Luna, Sara
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Seleznjev, Oleg
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Tordsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    How will your workload look like in 6 years?: Analyzing Wikimedia's workload2014Ingår i: Proceedings of the 2014 IEEE International Conference on Cloud Engineering (IC2E 2014) / [ed] Lisa O’Conner, IEEE Computer Society, 2014, s. 349-354Konferensbidrag (Refereegranskat)
    Abstract [en]

    Accurate understanding of workloads is key to efficient cloud resource management as well as to the design of large-scale applications. We analyze and model the workload of Wikipedia, one of the world's largest web sites. With descriptive statistics, time-series analysis, and polynomial splines, we study the trend and seasonality of the workload, its evolution over the years, and also investigate patterns in page popularity. Our results indicate that the workload is highly predictable with a strong seasonality. Our short term prediction algorithm is able to predict the workload with a Mean Absolute Percentage Error of around 2%.

  • 9.
    Ali-Eldin, Ahmed
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Seleznjev, Oleg
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Sjöstedt-de Luna, Sara
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Tordsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Measuring cloud workload burstiness2014Ingår i: 2014 IEEE/ACM 7th International Conference on Utility and Cloud Computing (UCC), IEEE conference proceedings, 2014, s. 566-572Konferensbidrag (Refereegranskat)
    Abstract [en]

    Workload burstiness and spikes are among the main reasons for service disruptions and decrease in the Quality-of-Service (QoS) of online services. They are hurdles that complicate autonomic resource management of datacenters. In this paper, we review the state-of-the-art in online identification of workload spikes and quantifying burstiness. The applicability of some of the proposed techniques is examined for Cloud systems where various workloads are co-hosted on the same platform. We discuss Sample Entropy (SampEn), a measure used in biomedical signal analysis, as a potential measure for burstiness. A modification to the original measure is introduced to make it more suitable for Cloud workloads.

  • 10.
    Ali-Eldin, Ahmed
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Tordsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kihl, Maria
    Lund University.
    WAC: A Workload analysis and classification tool for automatic selection of cloud auto-scaling methodsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Autoscaling algorithms for elastic cloud infrastructures dynami-cally change the amount of resources allocated to a service ac-cording to the current and predicted future load. Since there areno perfect predictors, no single elasticity algorithm is suitable foraccurate predictions of all workloads. To improve the quality ofworkload predictions and increase the Quality-of-Service (QoS)guarantees of a cloud service, multiple autoscalers suitable for dif-ferent workload classes need to be used. In this work, we intro-duce WAC, a Workload Analysis and Classification tool that as-signs workloads to the most suitable elasticity autoscaler out of aset of pre-deployed autoscalers. The workload assignment is basedon the workload characteristics and a set of user-defined Business-Level-Objectives (BLO). We describe the tool design and its maincomponents. We implement WAC and evaluate its precision us-ing various workloads, BLO combinations and state-of-the-art au-toscalers. Our experiments show that, when the classifier is tunedcarefully, WAC assigns between 87% and 98.3% of the workloadsto the most suitable elasticity autoscaler.

  • 11.
    Ali-Eldin, Ahmed
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Tordsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kihl, Maria
    Department of Electrical and Information Technology, Lund University, Lund, Sweden.
    Workload Classification for Efficient Auto-Scaling of Cloud Resources2013Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Elasticity algorithms for cloud infrastructures dynamically change the amount of resources allocated to a running service according to the current and predicted future load. Since there is no perfect predictor, and since different applications’ workloads have different characteristics, no single elasticity algorithm is suitable for future predictions for all workloads. In this work, we introduceWAC, aWorkload Analysis and Classification tool that analyzes workloads and assigns them to the most suitable elasticity controllers based on the workloads’ characteristics and a set of business level objectives.

    WAC has two main components, the analyzer and the classifier. The analyzer analyzes workloads to extract some of the features used by the classifier, namely, workloads’ autocorrelations and sample entropies which measure the periodicity and the burstiness of the workloads respectively. These two features are used with the business level objectives by the clas-sifier as the features used to assign workloads to elasticity controllers. We start by analyzing 14 real workloads available from different applications. In addition, a set of 55 workloads is generated to test WAC on more workload configurations. We implement four state of the art elasticity algorithms. The controllers are the classes to which the classifier assigns workloads. We use a K nearest neighbors classifier and experiment with different workload combinations as training and test sets. Our experi-ments show that, when the classifier is tuned carefully, WAC correctly classifies between 92% and 98.3% of the workloads to the most suitable elasticity controller.

  • 12.
    Ali-Eldin Hassan, Ahmed
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Workload characterization, controller design and performance evaluation for cloud capacity autoscaling2015Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis studies cloud capacity auto-scaling, or how to provision and release re-sources to a service running in the cloud based on its actual demand using an auto-matic controller. As the performance of server systems depends on the system design,the system implementation, and the workloads the system is subjected to, we focuson these aspects with respect to designing auto-scaling algorithms. Towards this goal,we design and implement two auto-scaling algorithms for cloud infrastructures. Thealgorithms predict the future load for an application running in the cloud. We discussthe different approaches to designing an auto-scaler combining reactive and proactivecontrol methods, and to be able to handle long running requests, e.g., tasks runningfor longer than the actuation interval, in a cloud. We compare the performance ofour algorithms with state-of-the-art auto-scalers and evaluate the controllers’ perfor-mance with a set of workloads. As any controller is designed with an assumptionon the operating conditions and system dynamics, the performance of an auto-scalervaries with different workloads.In order to better understand the workload dynamics and evolution, we analyze a6-years long workload trace of the sixth most popular Internet website. In addition,we analyze a workload from one of the largest Video-on-Demand streaming servicesin Sweden. We discuss the popularity of objects served by the two services, the spikesin the two workloads, and the invariants in the workloads. We also introduce, a mea-sure for the disorder in a workload, i.e., the amount of burstiness. The measure isbased on Sample Entropy, an empirical statistic used in biomedical signal processingto characterize biomedical signals. The introduced measure can be used to charac-terize the workloads based on their burstiness profiles. We compare our introducedmeasure with the literature on quantifying burstiness in a server workload, and showthe advantages of our introduced measure.To better understand the tradeoffs between using different auto-scalers with differ-ent workloads, we design a framework to compare auto-scalers and give probabilisticguarantees on the performance in worst-case scenarios. Using different evaluation cri-teria and more than 700 workload traces, we compare six state-of-the-art auto-scalersthat we believe represent the development of the field in the past 8 years. Knowingthat the auto-scalers’ performance depends on the workloads, we design a workloadanalysis and classification tool that assigns a workload to its most suitable elasticitycontroller out of a set of implemented controllers. The tool has two main components;an analyzer, and a classifier. The analyzer analyzes a workload and feeds the analysisresults to the classifier. The classifier assigns a workload to the most suitable elasticitycontroller based on the workload characteristics and a set of predefined business levelobjectives. The tool is evaluated with a set of collected real workloads, and a set ofgenerated synthetic workloads. Our evaluation results shows that the tool can help acloud provider to improve the QoS provided to the customers.

  • 13. Asan, Noor Badariah
    et al.
    Hassan, Emadeldeen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Perez, Mauricio David
    Shah, Syaiful Redzwan Mohd
    Velander, Jacob
    Blokhuis, Taco J.
    Voigt, Thiemo
    Augustine, Robin
    Assessment of Blood Vessel Effect on Fat-Intrabody Communication Using Numerical and Ex-Vivo Models at 2.45 GHZ2019Ingår i: IEEE Access, E-ISSN 2169-3536, Vol. 7, s. 89886-89900Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The potential offered by the intra-body communication (IBC) over the past few years has resulted in a spike of interest for the topic, specifically for medical applications. Fat-IBC is subsequently a novel alternative technique that utilizes fat tissue as a communication channel. This work aimed to identify such transmission medium and its performance in varying blood-vessel systems at 2.45 GHz, particularly in the context of the IBC and medical applications. It incorporated three-dimensional (3D) electromagnetic simulations and laboratory investigations that implemented models of blood vessels of varying orientations, sizes, and positions. Such investigations were undertaken by using ex-vivo porcine tissues and three blood-vessel system configurations. These configurations represent extreme cases of real-life scenarios that sufficiently elucidated their principal influence on the transmission. The blood-vessel models consisted of ex-vivo muscle tissues and copper rods. The results showed that the blood vessels crossing the channel vertically contributed to 5.1 dB and 17.1 dB signal losses for muscle and copper rods, respectively, which is the worst-case scenario in the context of fat-channel with perturbance. In contrast, blood vessels aligned-longitudinally in the channel have less effect and yielded 4.5 dB and 4.2 dB signal losses for muscle and copper rods, respectively. Meanwhile, the blood vessels crossing the channel horizontally displayed 3.4 dB and 1.9 dB signal losses for muscle and copper rods, respectively, which were the smallest losses among the configurations. The laboratory investigations were in agreement with the simulations. Thus, this work substantiated the fat-IBC signal transmission variability in the context of varying blood vessel configurations.

  • 14.
    Baskar, Jayalakshmi
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Lindgren, Helena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Human-Agent Dialogues on Health Topics - An Evaluation Study2015Ingår i: Highlights of practical applications of agents, multi-agent systems, and sustainability: The PAAMS Collection, PAAMS 2015, 2015, s. 28-39Konferensbidrag (Refereegranskat)
    Abstract [en]

    A common conversation between an older adult and a nurse about health-related issues includes topics such as troubles with sleep, reasons for walking around nighttime, pain conditions, etc. This dialogue emerges from the participating human's lines of thinking, their roles, needs and motives, while switching between topics as the dialogue unfolds. This paper presents a dialogue system that enables a human to engage in a dialogue with a software agent to reason about health-related issues in a home environment. The purpose of this work is to conduct a pilot evaluation study of a prototype system for human-agent dialogues, which is built upon a set of semantic models and integrated in a web application designed for older adults. Focus of the study was to receive qualitative results regarding purpose and content of the agent-based dialogue system, and to evaluate a method for the agent to evaluate its behavior based on the human agent's perception of appropriateness of moves. The participants include five therapists and 11 older adults. The results show users' feedback on the purpose of dialogues and the appropriateness of dialogues presented to them during the interaction with the software agent.

  • 15. Bauer,, André
    et al.
    Herbst, Nikolas
    Spinner, Simon
    Ali-Eldin, Ahmed
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kounev, Samuel
    Chameleon: A Hybrid, Proactive Auto-Scaling Mechanism on a Level-Playing Field2018Ingår i: IEEE Transactions on Parallel and Distributed Systems, ISSN 1045-9219, E-ISSN 1558-2183Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Auto-scalers for clouds promise stable service quality at low costs when facing changing workload intensity. The major public cloud providers provide trigger-based auto-scalers based on thresholds. However, trigger-based auto-scaling has reaction times in the order of minutes. Novel auto-scalers from literature try to overcome the limitations of reactive mechanisms by employing proactive prediction methods. However, the adoption of proactive auto-scalers in production is still very low due to the high risk of relying on a single proactive method.

  • 16. Bauer, André
    et al.
    Herbst, Nikolas
    Spinner, Simon
    Ali-Eldin, Ahmed
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. UMass, Amherst, MA, USA.
    Kounev, Samuel
    Chameleon: A Hybrid, Proactive Auto-Scaling Mechanism on a Level-Playing Field2019Ingår i: IEEE Transactions on Parallel and Distributed Systems, ISSN 1045-9219, E-ISSN 1558-2183, Vol. 30, nr 4, s. 800-813Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Auto-scalers for clouds promise stable service quality at low costs when facing changing workload intensity. The major public cloud providers provide trigger-based auto-scalers based on thresholds. However, trigger-based auto-scaling has reaction times in the order of minutes. Novel auto-scalers from literature try to overcome the limitations of reactive mechanisms by employing proactive prediction methods. However, the adoption of proactive auto-scalers in production is still very low due to the high risk of relying on a single proactive method. This paper tackles the challenge of reducing this risk by proposing a new hybrid auto-scaling mechanism, called Chameleon, combining multiple different proactive methods coupled with a reactive fallback mechanism. Chameleon employs on-demand, automated time series-based forecasting methods to predict the arriving load intensity in combination with run-time service demand estimation to calculate the required resource consumption per work unit without the need for application instrumentation. We benchmark Chameleon against five different state-of-the-art proactive and reactive auto-scalers one in three different private and public cloud environments. We generate five different representative workloads each taken from different real-world system traces. Overall, Chameleon achieves the best scaling behavior based on user and elasticity performance metrics, analyzing the results from 400 hours aggregated experiment time.

  • 17.
    Bayuh Lakew, Ewnetu
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Birke, Robert
    Perez, Juan F.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Chen, Lydia Y.
    SmallTail: Scaling Cores and Probabilistic Cloning Requests for Web Systems2018Ingår i: 15TH IEEE INTERNATIONAL CONFERENCE ON AUTONOMIC COMPUTING (ICAC 2018), IEEE , 2018, s. 31-40Konferensbidrag (Refereegranskat)
    Abstract [en]

    Users quality of experience on web systems are largely determined by the tail latency, e.g., 95th percentile. Scaling resources along, e.g., the number of virtual cores per VM, is shown to be effective to meet the average latency but falls short in taming the latency tail in the cloud where the performance variability is higher. The prior art shows the prominence of increasing the request redundancy to curtail the latency either in the off-line setting or without scaling-in cores of virtual machines. In this paper, we propose an opportunistic scaler, termed SmallTail, which aims to achieve stringent targets of tail latency while provisioning a minimum amount of resources and keeping them well utilized. Against dynamic workloads, SmallTail simultaneously adjusts the core provisioning per VM and probabilistically replicates requests so as to achieve the tail latency target. The core of SmallTail is a two level controller, where the outer loops controls the core provision per distributed VMs and the inner loop controls the clones in a finer granularity. We also provide theoretical analysis on the steady-state latency for a given probabilistic replication that clones one out of N arriving requests. We extensively evaluate SmallTail on three different web systems, namely web commerce, web searching, and web bulletin board. Our testbed results show that SmallTail can ensure the 95th latency below 1000 ms using up to 53% less cores compared to the strategy of constant cloning, whereas scaling-core only solution exceeds the latency target by up to 70%.

  • 18.
    Bensch, Suna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Björklund, Johanna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kutrib, Martin
    Institut fur Informatik, Universität Giessen.
    Deterministic Stack Transducers2016Ingår i: Implementation and Application of Automata / [ed] Yo-Sub Han and Kai Salomaa, Springer, 2016, s. 27-38Konferensbidrag (Refereegranskat)
    Abstract [en]

    We introduce and investigate stack transducers, which are one-way stack automata with an output tape. A one-way stack automaton is a classical pushdown automaton with the additional ability to move the stack head inside the stack without altering the contents. For stack transducers, we distinguish between a digging and a non-digging mode. In digging mode, the stack transducer can write on the output tape when its stack head is inside the stack, whereas in non-digging mode, the stack transducer is only allowed to emit symbols when its stack head is at the top of the stack. These stack transducers have a motivation from natural language interface applications, as they capture long-distance dependencies in syntactic, semantic, and discourse structures.We study the computational capacity for deterministic digging and non-digging stack transducers, as well as for their non-erasing and checking versions. We finally show that even for the strongest variant of stack transducers the stack languages are regular.

  • 19.
    Bensch, Suna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Björklund, Johanna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kutrib, Martin
    Deterministic Stack Transducers2017Ingår i: International Journal of Foundations of Computer Science, ISSN 0129-0541, Vol. 28, nr 5, s. 583-601Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We introduce and investigate stack transducers, which are one-way stack automata with an output tape. A one-way stack automaton is a classical pushdown automaton with the additional ability to move the stack head inside the stack without altering the contents. For stack transducers, we distinguish between a digging and a non-digging mode. In digging mode, the stack transducer can write on the output tape when its stack head is inside the stack, whereas in non-digging mode, the stack transducer is only allowed to emit symbols when its stack head is at the top of the stack. These stack transducers have a motivation from natural-language interface applications, as they capture long-distance dependencies in syntactic, semantic, and discourse structures. We study the computational capacity for deterministic digging and non-digging stack transducers, as well as for their non-erasing and checking versions. We finally show that even for the strongest variant of stack transducers the stack languages are regular.

  • 20.
    Bensch, Suna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kutrib, Martin
    Institut fuer Informatik, Universität Giessen.
    Malcher, Andreas
    Institut fuer Informatik, Universität Giessen.
    Extended Uniformly Limited T0L Languages and Mild Context-Sensitivity2016Ingår i: Eight Workshop on Non-Classical Models of Automata and Applications (NCMA 2016): Short Papers / [ed] Henning Bordihn, Rudolf Freund, Benedek Nagy, and György Vaszil, Wien: Institut für Computersprachen , 2016, s. 35-46Konferensbidrag (Refereegranskat)
    Abstract [en]

    We study the fixed membership problem for k-uniformly-limited and propagating ET0L systems (kulEPT0L systems). To this end, the algorithm given in [7] is applied. It follows that kulEPT0L languages are parsable in polynomial time. Since kulEPT0L languages are semi-linear [1] and kulEPT0L systems generate certain non-context-free languages, which capture the non-context-free phenomena occurring in natural languages, this is the last building block to show that kulEPT0L languages, for k ≥ 2, belong to the family of mildly context-sensitive languages.

  • 21.
    Bergvik, David
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Designing experiences for virtual reality, in virtual reality: A design process evaluation2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Creating immersive experiences for virtual reality (VR) presents new design opportunities and challenges that do not appear when creating experiences on a screen. Creating prototypes and exploring concepts in VR is today limited to professionals with previous knowledge in 3D application development, and testing 3D experiences requires the usage of an Head-Mounted Display (HMD), which forces professionals to switch medium from the computer to an HMD. With new advances in this field, there have to be new solutions to these challenges. The goal of this thesis is to explore how VR technology can be utilized in the experience design process for VR. This is achieved through a literature study and conducting expert interviews, followed by a hardware evaluation of different HMDs and concept creation using rapid prototyping. From the interviews, a number of issues could be identified that correlates with the research from the literature study. Based on these findings, two phases were identified as suitable for further improvements; Concept prototyping and testing/tweaking of a created experience. Lo-fi and hi-fi prototypes of a virtual design tool were developed for HTC Vive and Google Daydream, which were selected based on the hardware evaluation. The prototypes are designed and developed, then tested using a Wizard of Oz approach. The purpose of the prototypes is to solve some of the issues when designing immersive experiences for HMDs in the suitable experience design phases that were identified by analyzing the interview results. An interactive testing suite for HTC Vive was developed for testing and evaluation of the final prototype, to verify the validity of the concept. Using Virtual Reality as a medium for designing virtual experiences is a promising way of solving current issues within this technological field that are identified in this thesis. Tools for object creation and manipulation will aid professionals when exploring new concepts as well as editing and testing existing immersive experiences. Furthermore, using a Wizard of Oz approach to test VR prototypes significantly improves the prototype quality without compromising the user experience in this medium. 

  • 22.
    Bohman, Dan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Single Sign On med Azure AD Connect2016Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Den här rapporten handlar om Azure AD Connect och Single/Simplified Sign On. Användare och kunder idag ställer större krav för enklare inloggning och en mer sömlös upplevelse för åtkomst till alla IT-tjänster. Microsoft har nyligen släppt verktyget Azure AD Connect för synkronisering av lösenord mellan Active Directory och molntjänsterna Office365, Azure och 1000-tal SaaS ”Software as a service” applikationer. TeamNorr IT-partner är ett IT företag som riktar in sig på att leverera Microsofts produkter till sina kunder och vill därför veta mer kring Azure AD Connect, vad som krävs och hur det konfigureras.

    Single Sign On har betydelsen att bara behöver logga in en gång för att sen slippa skriva in användare och lösenord för att komma åt de applikationer som har stöd för Single Sign On. Federerad domän är det som ger bäst och säkrast upplevelse med Single Sign On. Simplified Sign On gör att samma användarnamn och lösenord används för inloggning, ingen automatisk inloggning sker.

    Azure AD Connect är verktyget som installerar de roller som behövs för att köra Single Sign On eller Simplified Sign On. Som standard installeras en synkroniseringsmotor som ska hålla koll på att informationen om användarna/grupperna och lösenorden stämmer mellan det lokala Active Directory och Azure Active Directory eller den federerade domänen.

    Det synkroniseringsmotorn tar med när den synkroniserar bestäms av de regler som satts upp. Används lösningen med Password Sync så tillkommer inga extra roller. Väljs istället en Federerad domän så installeras 2 extra roller som heter Federation(AD FS) och Web Application Proxy(WAP). Rollerna sköter autentisering av användarna istället för Microsofts autentisering. På servrarna som hostar rollerna krävs en viss grundprestanda beroende på storlek av Active Directory och antal användare anslutna för att det ska fungera tillfredsställande.

  • 23.
    Bräne, Arvid
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    User Experience Design for Children: Developing and Testing a UX Framework2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Designing good digital experiences for children can be difficult; designers have to consider children's cognitive and motor skill limitations, understand their target audience, create something entertaining and educational, comply with national and international jurisdiction, and at the same time appeal to parents. We set out to create a general framework which designers and developers can use as a foundation and testing ground for their digital products in the field of user experience.

    The methods used during the thesis include interviews, literature studies, user testing, case studies, personas, prototyping, and more. The results created are primarily user experience guidelines packaged in a Theoretical Framework, user testing conclusions, along with suggestions on improving the current Lego Star Wars: Force Builders application, a few in the form of prototypes.

  • 24.
    Brännback, Andreas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    FTTX-Analysverktyg anpassat för Telias nät2018Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Ett verktyg har utvecklats i programmeringsspråket Python, som analyserar status för uppkopplingar hos Fibre to the X (FTTX)-kunder i Telias nät. Systemet består av en moduluppdelad struktur, där alla analysfunktioner av samhörande typer är uppbyggda i egna moduler. Alla moduler lagras som individuella kodfiler. Systemet är designat för att enkelt kunna vidareutvecklas genom att tillägga fler analysmoduler i framtida projekt.

    För att utföra en analys på en specifik kund, hämtar systemet tekniska dataparametrar via den switch som kunden sitter uppkopplad mot. Dessa parametrar jämförs därefter med förbestämda värden för att hitta avvikelser. Simple network management protocol (SNMP) och Telnet är de primära protokollen som används för att hämta relevant data.

    Systemet har enbart Hypertext Transfer Protocol (HTTP) som input och output. Resultatet av en analys, redovisas som Extensible Markup Language (XML) mot den server som ursprungligen ställde förfrågan till att starta en analys. XML svaret innehåller både tekniska dataparametrar kring kundens uppkoppling samt ett analyssvar baserat på dessa tekniska parametrar.

    Utförligheten i svaret på en utförd analys varierar en aning beroende på switchtypen kunden sitter uppkopplad mot. Switchar av äldre hårdvarutyper presenterar generellt sett mindre kundportsdata jämfört med modernare varianter. Mindre kundportsdata leder till sämre utförlighet i analyssvaret. Därför lämpar sig detta analysverktyg bättre mot de modernare switcharna som finns i Telias nät.

  • 25.
    Buckland, Philip I.
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet.
    Freeing information to the people: Using the past to aid the future2011Ingår i: International Innovation - Disseminating Science Research and Technology, ISSN 2041-4552, nr 4, s. 51-53Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    Dr Philip Buckland discusses his recent project SEAD: the web-accessible scientific database that crosses archaeological and environmental disciplines. 

    Disciplines as diverse as anthropology and palaeoecology take an interest in our environment and how we have treated it. The Strategic Environmental Archaeology Database aims to create a multi-proxy, GIS-ready database for environmental and archaeological data to aid multidisciplinary research

  • 26.
    Camillo, Frédéric
    et al.
    University of Toulouse / ENSEEIHT.
    Caron, Eddy
    University of Lyon / École Normale Supérieure de Lyon.
    Guivarch, Ronan
    University of Toulouse / ENSEEIHT.
    Hurault, Aurélie
    University of Toulouse / ENSEEIHT.
    Klein, Cristian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Pérez, Christian
    University of Lyon / INRIA.
    Resource Management Architecture for Fair Scheduling of Optional Computations2013Ingår i: 2013 Eighth International Conference on P2P, Parallel, Grid, Cloud and Internet Computing: 3PGCIC 2013 / [ed] Fatos Xhafa, Leonard Barolli, Dritan Nace, Salvatore Vinticinque and Alain Bui, IEEE Computer Society, 2013, s. 113-120Konferensbidrag (Refereegranskat)
    Abstract [en]

    Most HPC platforms require users to submit a pre-determined number of computation requests (also called jobs). Unfortunately, this is cumbersome when some of the computations are optional, i.e., they are not critical, but their completion would improve results. For example, given a deadline, the number of requests to submit for a Monte Carlo experiment is difficult to choose. The more requests are completed, the better the results are, however, submitting too many might overload the platform. Conversely, submitting too few requests may leave resources unused and misses an opportunity to improve the results.

    This paper introduces and solves the problem of scheduling optional computations. An architecture which auto-tunes the number of requests is proposed, then implemented in the DIET GridRPC middleware. Real-life experiments show that several metrics are improved, such as user satisfaction, fairness and the number of completed requests. Moreover, the solution is shown to be scalable.

  • 27.
    Chaudhry, Tanmay
    et al.
    SimScale GmbH, Germany.
    Doblander, Christoph
    Technische Universität München, Germany.
    Dammer, Anatol
    SimScale GmbH, Germany.
    Klein, Cristian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Jacobsen, Hans-Arno
    Technische Universität München, Germany.
    Retrofitting Admission Control in an Internet-Scale Application2016Rapport (Övrigt vetenskapligt)
    Abstract [en]

    In this paper we propose a methodology to retrofit admission control in an Internet-scale, production application. Admission control requires less effort to improve the availability of an application, in particular when making it scalable is costly. This can occur due to the integration of 3rd-party legacy code or handling large amounts of data, and is further motivated by lean thinking, which argues for building a minimum viable product to discover customer requirements.

    Our main contribution consists in a method to generate an amplified workload, that is realistic enough to test all kinds of what-if scenarios, but does not require an exhaustive transition matrix. This workload generator can then be used to iteratively stress-test the application, identify the next bottleneck and add admission control.

    To illustrate the usefulness of the approach, we report on our experience with adding admission control within SimScale, a Software-as-a-Service start-up for engineering simulations, that already features 50,000 users.

  • 28.
    Daniel, Johansson
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Drivrutin för I/O-moduler tillhörande obsolet styr- och övervakningssystem2015Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Syftet med arbetet var att lösa problem med kompatibilitet mellan ett gammalt och ett nytt styr- och övervakningssystem, då den tidigare använda utrustningen har blivit obsolet och inom kort måste ersättas av nyare. Uppgiften gick ut på att skapa en drivrutin för I/O-moduler tillhörande styr- och övervakningssystemet i30, till det nya systemet JACE genom att ta fram dokumentation över kommunikationen och sedan återskapa den.Dokumentationen över kommunikationen togs fram genom att övervaka styr- och övervakningssystemet i30 i en testmiljö medan signaler kontrollerat skickades. Verifiering av dokumentationen gjordes i utvecklingsmiljön för det nya styr- och övervakningssystemet JACE. Med verktyget FlexSerial Driver återskapades den grundläggande kommunikationen och upplägget för drivrutinen togs fram. Det grafiska gränssnittet för drivrutinen utvecklades med användarvänlighet i åtanke genom att analysera vilka de mest frekvent använda funktionerna var. Den kompletta drivrutinen skapades genom verktyget NDriver och programmerades i språket Java.Resultatet av arbetet är en komplett dokumentation av kommunikationen mellan i30 och dess I/O-moduler och en fungerande drivrutin med ett skalbart gränssnitt. Drivrutinen är ej fullkomligt testad och är inte redo för kommersiell användning.

  • 29. Durango, Jonas
    et al.
    Dellkrantz, Manfred
    Maggio, Martina
    Klein, Cristian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Papadopoulos, Alessandro Vittorio
    Hernandez-Rodriguez, Francisco
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Arzen, Karl-Erik
    Control-theoretical load-balancing for cloud applications with brownout2014Ingår i: 2014 IEEE 53RD ANNUAL CONFERENCE ON DECISION AND CONTROL (CDC), 2014, s. 5320-5327Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cloud applications are often subject to unexpected events like flash crowds and hardware failures. Without a predictable behaviour, users may abandon an unresponsive application. This problem has been partially solved on two separate fronts: first, by adding a self-adaptive feature called brownout inside cloud applications to bound response times by modulating user experience, and, second, by introducing replicas - copies of the applications having the same functionalities - for redundancy and adding a load-balancer to direct incoming traffic. However, existing load-balancing strategies interfere with brownout self-adaptivity. Load-balancers are often based on response times, that are already controlled by the self-adaptive features of the application, hence they are not a good indicator of how well a replica is performing. In this paper, we present novel load-balancing strategies, specifically designed to support brownout applications. They base their decision not on response time, but on user experience degradation. We implemented our strategies in a self-adaptive application simulator, together with some state-of-the-art solutions. Results obtained in multiple scenarios show that the proposed strategies bring significant improvements when compared to the state-of-the-art ones.

  • 30.
    Edvinsson, Joakim
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Webifiering av BidCon2014Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Consultec är ett ledande företag inom utveckling av IT-verktyg och tjänster anpassade för bygg- och installationsbranschen. De har identifierat ett behov från deras kunder att se över möjligheterna att göra ett av deras verktyg mer lättåtkomligt via en webb-applikation.Målet med detta projekt är att utvärdera om det är möjligt att publicera ett redan existerande program på en hemsida samt att ta fram en prototyp. Hemsidan som tagits fram visar ett grovt exempel över hur den färdiga produkten skulle kunna se ut.

  • 31.
    Ehatisham-ul-Haq, Muhammad
    et al.
    Faculty of Telecom and Information Engineering, University of Engineering and Technology, Taxila, Punjab, Pakistan.
    Awais Azam, Muhammad
    Faculty of Telecom and Information Engineering, University of Engineering and Technology, Taxila, Punjab, Pakistan.
    Naeem, Usman
    School of Architecture, Computing and Engineering, University of East London, United Kingdom.
    Ur Rèhman, Shafiq
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Khaild, Asra
    Department of Computer Science, COMSATS Institute of Information Technology, Wah Campus, Pakistan.
    Identifying smartphone users based on their activity patterns via mobile sensing2017Ingår i: Procedia Computer Science, ISSN 1877-0509, E-ISSN 1877-0509, Vol. 113, s. 202-209Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Smartphones are ubiquitous devices that enable users to perform many of their routine tasks anytime and anywhere. With the advancement in information technology, smartphones are now equipped with sensing and networking capabilities that provide context-awareness for a wide range of applications. Due to ease of use and access, many users are using smartphones to store their private data, such as personal identifiers and bank account details. This type of sensitive data can be vulnerable if the device gets lost or stolen. The existing methods for securing mobile devices, including passwords, PINs and pattern locks are susceptible to many bouts such as smudge attacks. This paper proposes a novel framework to protect sensitive data on smartphones by identifying smartphone users based on their behavioral traits using smartphone embedded sensors. A series of experiments have been conducted for validating the proposed framework, which demonstrate its effectiveness.

  • 32.
    Eklund, Patrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kortelainen, Jari
    Two approaches to System-of-Systems from Lative Logic point of view2017Ingår i: 6TH INTERNATIONAL YOUNG SCIENTIST CONFERENCE ON COMPUTATIONAL SCIENCE, YSC 2017 / [ed] Klimova, A Bilyatdinova, A Kortelainen, J Boukhanovsky, A, Elsevier, 2017, Vol. 119, s. 16-21Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper presents two approaches to model System-of-Systems on lative logic point of view. Lative logic is a general framework to construct building blocks of logic using Category Theory as its metalanguage. This approach reveals avenues to describe System of -Systems themselves, and to model information and processes they posers, using some reasonable modelling languages in a computational manner, thus, touching foundations of computational science. After presenting some preliminary notes, the paper explains the main steps to construct lative logics, and then give two approaches to System-of-System modelling. Finally, the paper presents a survey to some applications.

  • 33.
    Eklund, Pauline
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Implementering av ISOBUS på ECU vid Ålö AB2017Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    En seriell buss kallad ISOBUS baserat på CAN blir allt vanligare inom jordbruk- och skogsindustrin. Bussen reglerar hur kommunikationen mellan traktorer och redskap fungerar. Tidigare har varje redskap haft en egen monitor för att se över redskapets funktioner, vilket innebär att det kan bli många skärmar i traktorhytten. Med ISOBUS behövs bara en monitor, så kallad VT (Virtuell Terminal), oavsett tillverkare av redskapet. Syftet med detta examensarbete är att implementera ISOBUS på Ålö:s ECU (Electronic Control Unit) för att denna ska kunna presentera sina funktioner på VT. Målet är att integrera ett inköpt tredjeparts kommersiellt ISOBUS bibliotek på ECU. Arbetet för att uppnå ISOBUS kompatibilitet utan tredjepartsbiblioteket skall uppskattas, och om tid finns utföras. En objektpool baserat på Ålös existerande gränssnitt ska skapas, där objektpoolen är det grafiska interface som visas på VT. En demonstrator av ISOBUS VT skall sättas upp. För att implementera tredjepartsbiblioteket krävde biblioteket hårdvarufunktioner mot CANbussen. Hårdvarufunktionerna tar bland annat emot meddelanden från en buffert och skickar ut meddelanden direkt på bussen. För att biblioteket skulle vara igång och köra måste det initieras och ett periodiskt anrop göras till biblioteket. Resultatet är att biblioteket implementerades på ECU och att det flödar trafik mellan ECU och VT. För att uppnå ISOBUS kompatibilitet utan tredjepartsbibliotek måste det existerande protokollet på Ålös ECU bytas ut med ett grundstöd för ISOBUS. Sedan måste en egen del skrivas för att uppnå full kompatibilitet. Här behöver bland annat kommandon som ISOBUS standarden definierar mellan ECU och VT skrivas, samt callbackfunktioner som anropas då VT skickar kommando till ECU. Hantering av svar och felmeddelanden vid kommunikation måste också implementeras. Att uppnå ISOBUS kompatibilitet utan tredjepartsbibliotek hann inte utföras, däremot uppskattades arbetet och en översiktlig beskrivning om vad som behöver utföras gjordes. Slutsatsen är att det kräver väldigt mycket arbete och finläsning av standarden. Fördelen är att man får en inblick i hur systemet fungerar och möjligheten att påverka funktionaliteter själv. Objektpoolen utformades efter hur Ålös existerande gränssnitt ser ut. Menysystem implementerades, samt att streckdiagram och en cirkulär mätare har möjligheten att visa höjd och vinkel på traktorskopan. Olika sätt för att visa ett menysystem har diskuterats. Resultatet är en objektpool med grundläggande funktioner för Ålös gränssnitt, demonstratorn visar dessa funktionaliteter. Resultatet visar på att det går att få gränssnittet för VT ganska likt Ålös existerande, med vissa skillnader som typsnitt, bildkvalité och menyfunktioner.

  • 34.
    Emil, Ceder
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Detect misconnected Telia customers in the network2015Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Sammanfattning

    Projektet består i att skapa ett program som kan upptäcka fiber kunder som har blivit felkopplade på switchen som ansluter dem till Telias nätverk. Programmet kommer att jämföra kunden som är konfigurerad på porten mot personen som har mottagit Teliaroutern som sitter på porten. Om de inte stämmer överens så finns det en risk att kunden har blivit felkopplad.

    Jämförelsen kan göras på grund av det unika serie numret på Teliaroutern som är registrerad både i sessionsdatabasen över aktiva Telia routrar och databasen över produkter levererade till kunder. Detta kommer bara fungera för kunder med Telia routrar, men kommer fortfarande vara användbart då det ger en indikation om vilka switchar som eventuellt kan ha felkopplade kunder. Om det finns en felkopplad kund så är det stor risk att det finns fler.

    Programmet skapades med MySQL och PHP i formen av ett webbverktyg. Programmet kan köras mot valda switchar eller kan det köras mot alla aktiva Telia routrar och hitta kunder där jämnföring inte stämmer överens.

    För att programmet ska fungera så behövdes det tillgång till sessionsdatabasen över aktiva Telia routrar, databasen över kundens tjänster konfigurerade på porten och databasen över utskickade Telia routrar. Det är alltså tre olika system och på grund av tidsbegränsning så användes bara en del av informationen eller så hämtades informationen från testmiljöer.

    Med den tillgängliga informationen kunde programmet köras mot 8627 kunder och av dem så stämde inte 303 kunder överens i jämförelsen. Detta betyder inte nödvändigtvis att alla är felkopplade. I de flesta fall så var det en annan person i hushållet som hade tagit emot Teliaroutern än den personen som stod skriven på Teliatjänsten. Dessa fall kunde sorteras bort genom att bara ta fall där mottagaren av Teliaroutern också står skriven på en Teliatjänst. Efter denna utsortering så lämnades 57 kunder kvar av 303. Av de 57 kunderna så hade några av dem specialtjänster och vissa hade delat upp tjänsterna på två personer i samma hushåll. Efter att ha manuellt sorterat dem så fanns det 15 kunder kvar som troligen är felkopplade.

    Det finns fortfarande inget sätt att garantera att de 15 kunderna har blivit felkopplade, men det finns en stor risk att dem är felkopplade och om programmet hittar flera misstänkta felkopplingar på samma switch är mycket troligt att det finns felkopplade kunder.

  • 35. Farokhi, Soodeh
    et al.
    Lakew, Ewnetu Bayuh
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Klein, Cristian
    Brandic, Ivona
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Coordinating CPU and Memory Elasticity Controllers to Meet Service Response Time Constraints2015Ingår i: 2015 INTERNATIONAL CONFERENCE ON CLOUD AND AUTONOMIC COMPUTING (ICCAC), 2015, s. 69-80Konferensbidrag (Refereegranskat)
    Abstract [en]

    Vertical elasticity is recognized as a key enabler for efficient resource utilization of cloud infrastructure through fine-grained resource provisioning, e.g., allowing CPU cycles to be leased for as short as a few seconds. However, little research has been done to support vertical elasticity where the focus is mostly on a single resource, either CPU or memory, while an application may need arbitrary combinations of these resources at different stages of its execution. Nonetheless, the existing techniques cannot be readily used as-is without proper orchestration since they may lead to either under-or over-provisioning of resources and consequently result in undesirable behaviors such as performance disparity. The contribution of this paper is the design of an autonomic resource controller using a fuzzy control approach as a coordination technique. The novel controller dynamically adjusts the right amount of CPU and memory required to meet the performance objective of an application, namely its response time. We perform a thorough experimental evaluation using three different interactive benchmark applications, RUBiS, RUBBoS, and Olio, under workload traces generated based on open and closed system models. The results show that the coordination of memory and CPU elasticity controllers using the proposed fuzzy control provisions the right amount of resources to meet the response time target without over-committing any of the resource types. In contrast, with no coordinating between controllers, the behaviour of the system is unpredictable e.g., the application performance may be met but at the expense of over-provisioning of one of the resources, or application crashing due to severe resource shortage as a result of conflicting decisions.

  • 36.
    Forsberg, Evelina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Enterprise Voice Simulation (EVS) för mobila enheter i BYOD miljö.2014Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Denna rapport introducerar Umeå universitets bakgrund till införandet av Lync Server 2013 som etablerades stabilt år 2014. Det trådlösa nätverket vid Umeå universitet trafikeras av studenter och anställda med mobila enheter som smartphones och laptops. Vid användandet av mobila enheter stiger flödesströmningen I det trådlösa nätverket med olika typer av trafiker. I denna rapport omfattas närmare ”Voice UDP” och ”Lync Enterprise Voice” med fokus på trängselkontroller vid överföringar av RTP-trafik mellan mobila klienter och 802.11 för att identifiera kvalitén i Lync-samtal, ”VoIP over WLAN”. Metoden baserades på referenser med MOS-skala 1 till 5 i syfte att jämföra vilka mobila enheter som bör kvalificeras till bästa uppnådda QoE. Resultatet av de åtta framtagna mobila enheterna framvisade att Samsung Galaxy s2 toppade totala benchmark för minst tappade och flest passerade paket. iPhone 5 resulterade den sämsta mobila enheten för RTP-trafik med mest antal förlorade paket och lägst antal passerande paket.

    Benchmark:Benchmark värderas med totala summeringen av procent mätningsreferenser, Voice MOS, packet loss, max consecutive packet loss, jitter, peak jitter samt Round-Trip Delay både i upplänk och nedlänk.

  • 37.
    Gaggl, Sarah Alice
    et al.
    Technische Universität Dresden, Germany.
    Nieves, Juan CarlosUmeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.Strass, HannesUniversity of Leipzig, Germany.
    Arg-LPNMR 2016 proceedings: First International Workshop on Argumentation in Logic Programming and Non-Monotonic Reasoning2016Samlingsverk (redaktörskap) (Refereegranskat)
    Abstract [en]

    This volume contains the papers presented at Arg-LPNMR 2016: First International Workshop on Argumentation in Logic Programming and Nonmonotonic Reasoning held on July 8-10, 2016 in New York City, NY.

  • 38.
    Gaggl, Sarah Alice
    et al.
    Technische Universität Dresden, Germany.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Strass, Hannes
    Leipzig University, Germany.
    Torroni, Paolo
    University of Bologna, Italy.
    Preface: Argumentation and Logic Programming (Revised Selected Papers of ArgLP 2015)2017Ingår i: Fundamenta Informaticae, ISSN 0169-2968, E-ISSN 1875-8681, Vol. 155, nr 3Artikel i tidskrift (Övrigt vetenskapligt)
  • 39.
    Goggins, Sean P
    et al.
    Drexel University, USA.
    Jahnke, Isa
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för tillämpad utbildningsvetenskap, Interaktiva medier och lärande (IML).
    CSCL@work: making learning visible in unexpected online places across established boundaries2012Ingår i: International Journal of Sociotechnology and Knowledge Development, ISSN 1941-6253, Vol. 4, nr 3, s. 17-37Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We introduce Computer-Supported Collaborative Learning (CSCL) at the workplace (CSCL@Work) as a conceptual framework for bridging the knowledge of researchers in the field of CSCL to work-based learning. Research in the field of Organizational Learning emerged in 1978, and gained further attention in the 1990’s when challenges centered on the creation of organizational cultures to support existing knowledge sharing. In contemporary firms, shepherding the creation of new knowledge is of equal importance, and is driven by two primary research questions. First, how do organizations create new knowledge when the answer to a particular problem is not available within the firm? Second, what cultures of learning must and do exist to support solving problems when the answer is not known within an organization? Contemporary answers to these questions must recognize that learning is an implicit, often invisible component of work, and explicitly decouple the construct of learning from its main western institutionalization, the school. To advance thinking in this area, we undertook a meta analysis of 8 CSCL@Work cases and developed 3 design theses: 1) Learning occurs in unexpected and unusual online learning places, especially through Social Media. 2) Learning activities incorporate feedback from diverse people, who are not available within traditional organizational boundaries; 3) learning must be made visible across established boundaries. Designing explicit construction of new knowledge needs to be integrated into workplace practices today through pedagogical and technological design.

  • 40. Goumas, Georgios
    et al.
    Nikas, Konstantinos
    Lakew, Ewnetu Bayuh
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kotselidis, Christos
    Attwood, Andrew
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Flouris, Michail
    Foutris, Nikos
    Goodacre, John
    Grohmann, Davide
    Karakostas, Vasileios
    Koutsourakis, Panagiotis
    Kersten, Martin
    Lujan, Mikel
    Rustad, Einar
    Thomson, John
    Tomás, Luis
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Vesterkjaer, Atle
    Webber, Jim
    Zhang, Ying
    Koziris, Nectarios
    ACTiCLOUD: Enabling the Next Generation of Cloud Applications2017Ingår i: 2017 IEEE 37TH INTERNATIONAL CONFERENCE ON DISTRIBUTED COMPUTING SYSTEMS (ICDCS 2017) / [ed] Lee, K Liu, L, IEEE Computer Society, 2017, s. 1836-1845Konferensbidrag (Refereegranskat)
    Abstract [en]

    Despite their proliferation as a dominant computing paradigm, cloud computing systems lack effective mechanisms to manage their vast amounts of resources efficiently. Resources are stranded and fragmented, ultimately limiting cloud systems' applicability to large classes of critical applications that pose non-moderate resource demands. Eliminating current technological barriers of actual fluidity and scalability of cloud resources is essential to strengthen cloud computing's role as a critical cornerstone for the digital economy. ACTiCLOUD proposes a novel cloud architecture that breaks the existing scale-up and share-nothing barriers and enables the holistic management of physical resources both at the local cloud site and at distributed levels. Specifically, it makes advancements in the cloud resource management stacks by extending state-of-the-art hypervisor technology beyond the physical server boundary and localized cloud management system to provide a holistic resource management within a rack, within a site, and across distributed cloud sites. On top of this, ACTiCLOUD will adapt and optimize system libraries and runtimes (e.g., JVM) as well as ACTiCLOUD-native applications, which are extremely demanding, and critical classes of applications that currently face severe difficulties in matching their resource requirements to state-of-the-art cloud offerings.

  • 41.
    Hegner, Stephen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Characterization of optimal complements of database views defined by projection2011Ingår i: Semantics in Data and Knowledge Bases: 4th International Workshop, SDKB 2010, Bordeaux, France, July 5, 2010, Revised Selected Papers / [ed] Klaus-Dieter Schewe and Bernhard Thalheim, Berlin: Springer Berlin/Heidelberg, 2011, s. 73-95Konferensbidrag (Refereegranskat)
  • 42.
    Hegner, Stephen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    FD Covers and Universal Complements of Simple Projections2012Ingår i: Foundations of Information and Knowledge Systems -: 7th International Symposium, FoIKS 2012, Kiel, Germany, March 5-9, 2012. Proceedings / [ed] Thomas Lukasiewicz, Attila Sali, Heidelberg: Springer Berlin/Heidelberg, 2012, s. 184-202Konferensbidrag (Refereegranskat)
    Abstract [en]

    The constant-complement strategy, in which the admissible updates to a given view are those which hold a second complementary view constant, remains one of the most attractive formalisms for identifying suitable translation mechanisms for updates to views of database schemata. However, in general, it suffers from the drawback that the reflections of view updates to the main schema can depend upon the choice of complement in various ways. To overcome this drawback completely, a special kind of complement, called a universal complement, is required. In this paper, sufficient conditions for the existence of such a complement are established for a classical but nevertheless very important setting — views defined by simple projection of a universal relational schema constrained by functional dependencies (FDs). Certain uniqueness properties of covers of these dependencies prove critical in the characterization. The results are extended to quasi-universal complements, which are unique up to exchange of equivalent attributes, thus recapturing certain situations for which unique covers do not exist.

  • 43.
    Hegner, Stephen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Independent Update Reflections on Interdependent Database Views2012Ingår i: Conceptual Modelling and Its Theoretical Foundations: Essays Dedicated to Bernhard Thalheim on the Occasion of His 60th Birthday / [ed] Antje Düsterhöft, Meike Klettke, Klaus-Dieter Schewe, Heidelberg: Springer Berlin/Heidelberg, 2012, s. 101-115Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    The problem of identifying suitable view-update strategies is typically addressed in the context of a single view. However, it is often the case that several views must co-exist; the challenge is then to find strategies which allow one view to be updated without affecting the other. The classical constant-complement strategy can provide a solution to this problem; however, both the context and the admissible updates are quite limited. In this work, the updates which are possible within this classical approach are extended substantially via a technique which considers only the states which are reachable from a given initial configuration. The results furthermore do not depend upon complementation, and thus are readily extensible to settings involving more than two views.

  • 44.
    Hegner, Stephen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Information-based distance measures and the canonical reflection of view updates2011Ingår i: Annals of Mathematics and Artificial Intelligence, ISSN 1012-2443, E-ISSN 1573-7470, Vol. 63, nr 3-4, s. 317-355Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For the problem of reflecting an update on a database view to the main schema, the constant-complement strategies are precisely those which avoid all update anomalies, and so define the gold standard for well-behaved solutions to the problem. However, the families of view updates which are supported under such strategies are limited, so it is sometimes necessary to go beyond them, albeit in a systematic fashion. In this work, an investigation of such extended strategies is initiated for relational schemata. The approach is to characterize the information content of a database instance, and then require that the optimal reflection of a view update to the main schema embody the least possible change of information. The key property is identified to be strong monotonicity of the view, meaning that view insertions may always be reflected as insertions to the main schema, and likewise for deletions. In that context it is shown that for insertions and deletions, an optimal update, entailing the least change of information, exists and is unique up to isomorphism for wide classes of constraints.

  • 45.
    Henriksson, Alexander
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Utvecklingsprojekt för produktionsverktyg i kulturverksamhet: Database development in a cultural environment2015Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Projektet visar hur man med relativt lite kunskap om programmering kan ta fram en lösning som både är cross-platform och enkel att underhålla och vidareutveckla med ytterligare funktioner i framtiden. Systemet är gjort i Filemaker Pro 13/14 som också är klienten för Mac OS X och används för mobila enheter via Filemaker Go 13/14.

    Personalen på kostymavdelningen på NorrlandsOperan har tidigare arbetat med en struktur där information och bilder kring produktionen sparats i olika Excel eller Word-dokument för att sen sparas på en gemensam filserver. Detta arbetssätt skapar problem kring dokumentation, att hitta information och att jobba mobilt.

    Lösningen är framtagen för att understödja personalen i deras arbete och följer en tydlig ordning med vilka objekt som är relaterade till vilka andra objekt. Det är lätt att hitta relevant information och att söka på flera olika parametrar för att hitta information. Det går att använda samma artister i flera olika produktioner för att behålla data som mått på artister och bilder på artister. Det finns möjlighet att söka på en eller flera artister och få en lista över vilka kostymer de ska använda sig av i föreställningen och i vilken scen kostymerna ska användas. 

  • 46.
    Ibidunmoye, Olumuyiwa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Performance anomaly detection and resolution for autonomous clouds2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Grundläggande egenskaper för datormoln såsom resursdelning och självbetjäning driver ett växande nyttjande av molnet för internettjänster. En följd av denna tillväxt är att den underliggande molninfrastrukturens ökande storlek och komplexitet samt fluktuerade arbetsbelastning orsakar prestandaincidenter med högre frekvens än någonsin tidigare. En konsekvens av detta blir omfattande inverkan på intäkter, tillförlitlighet och rykte för de som äger tjänsterna. Det har därför blivit viktigt att snabbt och effektivt hantera prestandaincidenter med avseende på upptäckt, diagnos och korrigering. Även om andra aspekter av resurshantering för datormoln, som övervakning och resursallokering, på senare tid automatiserats i allt högre grad så är automatiserad hantering av prestandaincidenter fortfarande ett stort problem.

    Denna avhandling fokuserar på hur prestandahanteringen i molndatacenter kan förbättras genom användning av dataanalystekniker på de stora datamängder som produceras i de system som monitorerar prestanda hos datorresurser och tjänster. I synnerhet undersöks tekniker och modeller för automatisk upptäckt och förebyggande av prestandaanomalier i datormoln. För att kartlägga utvecklingen inom forskningsområdet presenterar vi resultatet av en omfattande undersökning av befintliga forskningsbidrag som behandlar olika aspekter av hantering av prestandaproblem inom i relevanta tillämpningsområden. Vi diskuterar design och utvärdering av analysmodeller och algoritmer för att upptäcka prestandaanomalier i realtid hos resurser och tjänster. Vi diskuterar också utformningen av ett maskininlärningsbaserat tillvägagångssätt för att mildra prestandaförluster genom att aktivt driva tjänsternas kvalitet från oönskade tillstånd till ett önskat målläge genom inkrementell kapacitetoptimering. Forskningsmetoderna som används i denna avhandling innefattar experiment på verkliga virtualiserade testmiljöer för att utvärdera aspekter av föreslagna tekniker medan andra aspekter utvärderas med hjälp av belastningsmönster från verkliga datacenter.

    Insikter och resultat från denna avhandling kan användas av både moln- och tjänsteoperatörer för att bättre automatisera detekteringen av prestandaproblem, inklusive dess diagnos och korrigering. Resultaten har också potential att uppmuntra vidare forskning inom området samtidigt som de är användbara inom relaterade områden som internet-av-saker, industriella sensorer, och storskaligt distribuerade moln eller telekomnätverk.

  • 47.
    Ibidunmoye, Olumuyiwa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Performance problem diagnosis in cloud infrastructures2016Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Cloud datacenters comprise hundreds or thousands of disparate application services, each having stringent performance and availability requirements, sharing a finite set of heterogeneous hardware and software resources. The implication of such complex environment is that the occurrence of performance problems, such as slow application response and unplanned downtimes, has become a norm rather than exception resulting in decreased revenue, damaged reputation, and huge human-effort in diagnosis. Though causes can be as varied as application issues (e.g. bugs), machine-level failures (e.g. faulty server), and operator errors (e.g. mis-configurations), recent studies have attributed capacity-related issues, such as resource shortage and contention, as the cause of most performance problems on the Internet today. As cloud datacenters become increasingly autonomous there is need for automated performance diagnosis systems that can adapt their operation to reflect the changing workload and topology in the infrastructure. In particular, such systems should be able to detect anomalous performance events, uncover manifestations of capacity bottlenecks, localize actual root-cause(s), and possibly suggest or actuate corrections.

    This thesis investigates approaches for diagnosing performance problems in cloud infrastructures. We present the outcome of an extensive survey of existing research contributions addressing performance diagnosis in diverse systems domains. We also present models and algorithms for detecting anomalies in real-time application performance and identification of anomalous datacenter resources based on operational metrics and spatial dependency across datacenter components. Empirical evaluations of our approaches shows how they can be used to improve end-user experience, service assurance and support root-cause analysis. 

  • 48.
    Ibidunmoye, Olumuyiwa
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Ali-Reza, Rezaie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Adaptive Anomaly Detection in Performance Metric Streams2018Ingår i: IEEE Transactions on Network and Service Management, ISSN 1932-4537, E-ISSN 1932-4537, Vol. 15, nr 1, s. 217-231Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Continuous detection of performance anomalies such as service degradations has become critical in cloud and Internet services due to impact on quality of service and end-user experience. However, the volume and fast changing behaviour of metric streams have rendered it a challenging task. Many diagnosis frameworks often rely on thresholding with stationarity or normality assumption, or on complex models requiring extensive offline training. Such techniques are known to be prone to spurious false-alarms in online settings as metric streams undergo rapid contextual changes from known baselines. Hence, we propose two unsupervised incremental techniques following a two-step strategy. First, we estimate an underlying temporal property of the stream via adaptive learning and, then we apply statistically robust control charts to recognize deviations. We evaluated our techniques by replaying over 40 time-series streams from the Yahoo! Webscope S5 datasets as well as 4 other traces of real web service QoS and ISP traffic measurements. Our methods achieve high detection accuracy and few false-alarms, and better performance in general compared to an open-source package for time-series anomaly detection.

  • 49.
    Ibidunmoye, Olumuyiwa
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Blackbox Strategies for Detecting Service Performance Anomalies in Virtualized Environments2016Rapport (Övrigt vetenskapligt)
    Abstract [en]

    In order to prevent violation of service-level objectives and to guarantee good user experience, detection of symptoms such as slow application response, degraded transaction throughput, and service outages, is crucial. We propose a black-box approach for detecting such symptoms in service performance behaviour without intrusive application instrumentation. In case a known baseline behaviour exists, we employ kernel density estimation to discover deviations from a given set of baseline measurements. Conversely, when no baseline exists, we apply statistical process control charts on prediction errors obtained from Holt-Winter’s double exponential smoothing to identify anomalies in metric time-series. We evaluate our methods on tail response times traces collected from experiments conducted in a real testbed under realistic load and fault injections. Results show the applicability of our approach for improving service assurance and also demonstrate how service level anomalies correlate with system-level events such as resource contention and bottlenecks.

  • 50.
    Ibidunmoye, Olumuyiwa
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Francisco, Hernandez-Rodriguez
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Performance Anomaly Detection and Bottleneck Identification2015Ingår i: ACM Computing Surveys, ISSN 0360-0300, E-ISSN 1557-7341, Vol. 48, nr 1, artikel-id 4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to meet stringent performance requirements, system administrators must effectively detect undesirable performance behaviours, identify potential root causes and take adequate corrective measures. The problem of uncovering and understanding performance anomalies and their causes (bottlenecks) in different system and application domains is well studied. In order to assess progress, research trends and identify open challenges, we have reviewed major contributions in the area and present our findings in this survey. Our approach provides an overview of anomaly detection and bottleneck identification research as it relates to the performance of computing systems. By identifying fundamental elements of the problem, we are able to categorize existing solutions based on multiple factors such as the detection goals, nature of applications and systems, system observability, and detection methods.

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