Endre søk
Begrens søket
56789 351 - 400 of 435
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 351.
    Ripa, Viktor
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Elouaer, Jonas
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    En Säkerhetssyn2015Oppgave
    Abstract [sv]

    Vi vill få en insyn i hur säkerheten ser ut på kärnkraft- och kolkraftverk och hur framtiden ser ut för dem. Vad som kan förbättras och vad som hotar dem.

  • 352.
    Rodriguez, Pilar
    et al.
    Oulun Yliopisto, FIN.
    Mendes, Emilia
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik. Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för programvaruteknik.
    Turhan, Buran
    Oulun Yliopisto, FIN.
    Key Stakeholders' Value Propositions for Feature Selection in Software-intensive Products: An Industrial Case Study2018Inngår i: IEEE Transactions on Software Engineering, ISSN 0098-5589, E-ISSN 1939-3520Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Numerous software companies are adopting value-based decision making. However, what does value mean for key stakeholders making decisions? How do different stakeholder groups understand value? Without an explicit understanding of what value means, decisions are subject to ambiguity and vagueness, which are likely to bias them. This case study provides an in-depth analysis of key stakeholders' value propositions when selecting features for a large telecommunications company's software-intensive product. Stakeholder' value propositions were elicited via interviews, which were analyzed using Grounded Theory coding techniques (open and selective coding). Thirty-six value propositions were identified and classified into six dimensions: customer value, market competitiveness, economic value/profitability, cost efficiency, technology & architecture, and company strategy. Our results show that although propositions in the customer value dimension were those mentioned the most, the concept of value for feature selection encompasses a wide range of value propositions. Moreover, stakeholder groups focused on different and complementary value dimensions, calling to the importance of involving all key stakeholders in the decision making process. Although our results are particularly relevant to companies similar to the one described herein, they aim to generate a learning process on value-based feature selection for practitioners and researchers in general. IEEE

  • 353.
    Rosander, Oliver
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Ahlstrand, Jim
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Email Classification with Machine Learning and Word Embeddings for Improved Customer Support2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Classifying emails into distinct labels can have a great impact on customer support. By using machine learning to label emails the system can set up queues containing emails of a specific category. This enables support personnel to handle request quicker and more easily by selecting a queue that match their expertise.

    This study aims to improve the manually defined rule based algorithm, currently implemented at a large telecom company, by using machine learning. The proposed model should have higher F1-score and classification rate. Integrating or migrating from a manually defined rule based model to a machine learning model should also reduce the administrative and maintenance work. It should also make the model more flexible.

    By using the frameworks, TensorFlow, Scikit-learn and Gensim, the authors conduct five experiments to test the performance of several common machine learning algorithms, text-representations, word embeddings and how they work together.

    In this article a web based interface were implemented which can classify emails into 33 different labels with 0.91 F1-score using a Long Short Term Memory network.

    The authors conclude that Long Short Term Memory networks outperform other non-sequential models such as Support Vector Machines and ADABoost when predicting labels for emails.

  • 354.
    Routhu, Venkata Sai Kalyan
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Estimation of QoE aware sustainable throughput in relation to TCP throughput to evaluate the user experience2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

               Recent years the research focus began on “Quality of Experience” (QoE) that addresses user satisfaction level and improvement of service. The notation sustainable throughput, sometimes also called reliable throughput, ensures user satisfaction level at the same time requires an optimum resource to provide the service. In the context of communication, it becomes important to analyze user behavior with respect to network performance.

                Since the user is closer to the transport layer than the network layer, there opens a new domain to relate “QoE aware sustainable throughput” and “TCP throughput”. There is a need to further investigation of “QoE aware sustainable throughput” as it the one which sufficiently QoE, while “TCP throughput” is the result of a control process on a layer. Moreover, it is essential to estimate the QoE aware sustainable throughput based on HTTP streaming on the server and client application may result in a closer understanding of the nature of TCP in terms of user expectation.

                   In this study, we evaluated the performance of video streaming considering the TCP throughput in the presence of network disturbances, packet loss, and delay. The TCP packet behavior is observed in the experimental test setup. The quality assessment at which the QoE problems can still be kept at the desired level is determined. Mean opinion scores of the preferred use cases for the dash and non-dash server is used to estimate the relationship factor between “TCP throughput” and “QoE aware sustainable throughput”.

  • 355.
    Royar Sazdar, Rocan
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Evaluating usability aspects of a school photo mobile application2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Context. The market for mobile applications is expanding rapidly. Companies that have web-based applications are required to supply their costumerswith mobile applications to not fall behind and lose their costumers. Portinga web-based application to a mobile platform is not only about decreasing thesize of the web-pages’ content. To succeed in porting a web-based applicationto a mobile platform the usability of the application must remain the sameand possibly be improved, otherwise the consequence is that users becomefrustrated and leave the mobile application.

    Objectives. The objectives of this thesis is to investigate how to structureand display the features of a school photo web-based application to a mobileapplication, and keep the usability.

    Methods. A literature study has been done to find guidelines for designingmobile applications. Three mobile application prototypes have been devel-oped. The prototypes have been tested with usability tests in a laboratoryexperiment to find usability problems if such exists, and to identify the mostusable alternative. The usability tests have been done with the target groupof the mobile application.

    Results. The most usable prototype was identified. Also, a list of recommen-dations are compiled from the experiment (such as, provide help text underthe icons to clarify the content of the icon), and specific improvements thatcan be done to the most usable prototype is also compiled.

    Conclusions. As a conclusion, the used guidelines and usability heuristicssupported the design of the prototypes and helped to get user-friendly inter-faces. Prototype III obtained the best results in the usability tests. The resultsalso showed that the Prototype III can be further improved. It has also beenfound that related applications such as Instagram, can be helpful in order toget usable and user-friendly interfaces.

  • 356.
    Sagar, Susheel
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Sidorova, Yulia
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Sequence retriever for known, discovered, and user-specified molecular fragments2016Inngår i: 10TH INTERNATIONAL CONFERENCE ON PRACTICAL APPLICATIONS OF COMPUTATIONAL BIOLOGY & BIOINFORMATICS / [ed] Fdez-Riverola F.,De Paz J.F.,Rocha M.P.,Mayo F.J.D.,Mohamad M.S., Springer, 2016, Vol. 477, s. 51-58Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Typically, biological and chemical data are sequential, for example, as in genomic sequences or as in diverse chemical formats, such as InChI or SMILES. That poses a major problem for computational analysis, since the majority of the methods for data mining and prediction were developed to work on feature vectors. To address this challenge, a functionality of a Statistical Adapter has been proposed recently. It automatically converts parsable sequential input into feature vectors. During the conversion, insights are gained into the problem via finding regions of interest in the sequence and the level of abstraction for their representation, and the feature vectors are filled with the counts of interesting sequence fragments,-finally, making it possible to benefit from powerful vectorbased methods. For this submission, the Sequence Retriever has been added to the Adapter. While the Adapter performs the conversion: sequence → vector with the counts of interesting molecular fragments, the Retriever performs the mapping: molecular fragment → sequences from the database that contain this fragment.

  • 357.
    Sagar, Susheel
    et al.
    Blekinge Inst Technol, Master Programe Comp Sci, Karlskrona, Sweden..
    Skold, Lars
    Telenor, SWE.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Sidorova, Yulia
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Trajectory Segmentation for a Recommendation Module of a Customer Relationship Management System2017Inngår i: Proceedings - 2017 IEEE International Conference on Internet of Things, IEEE Green Computing and Communications, IEEE Cyber, Physical and Social Computing, IEEE Smart Data, iThings-GreenCom-CPSCom-SmartData 2017 / [ed] Wu, Y Min, G Georgalas, N AlDubi, A Jin, X Yang, L Ma, J Yang, P, IEEE , 2017, s. 1150-1155Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In business analytics some industries rely heavily on commercial geo-demographic segmentation systems (MOSAIC, ACORN, etc.), which are a universally strong predictor of user's behavior: from diabetes propensity and purchasing habits to political preferences. A segment is defined with a postcode of the client's home address. Recent research suggests that a mature competitor to geo-demographic segmentation is about to emerge: segmentation based on user mobility is reported to be a reliable proxy of social well-being of the neighborhood. In this submission, we have completed a user segmentation model based on clustering of user trajectories from the Call Detail Records covering one week of activity of one region in Sweden. The new segmentation has been compared against MOSAIC in the recommendation module of a customer relationship management system and has revealed better business options with regard to network exploitation and potential revenues. The implementation is available from the corresponding author (JS or LL) on request.

  • 358.
    Sagayam, K. M.
    et al.
    Karunya University, IND.
    Hemanth, D. J.
    Karunya University, IND.
    Vasanth, X. A.
    Karunya University, IND.
    Henesey, Lawrence
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för teknik och estetik. Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Ho, C. C.
    Multimedia University, Cyberjaya, MYS.
    Optimization of a HMM-based hand gesture recognition system using a hybrid cuckoo search algorithm2018Inngår i: Hybrid Metaheuristics for Image Analysis, Springer International Publishing , 2018, s. 87-114Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    The authors develop an advanced hand motion recognition system for virtual reality applications using a well defined stochastic mathematical approach. Hand gesture is a natural way of interaction with a computer by interpreting the primitive characteristics of gesture movement to the system. This concerns three basic issues: (1) there is no physical contact between the user and the system, (2) the rotation of the hand gesture can be determined by the geometric features, and (3) the model parameter must be optimized to improve measurement of performance. A comparative analysis of other classification techniques used in hand gesture recognition is carried out on the proposed work hybrid with the bio-inspired metaheuristic approach, namely the cuckoo search algorithm, for reducing the complex trajectory in the hidden Markov model (HMM) model. An experimental result is as to how to validate the HMM model, based on the cost value of the optimizer, in order to improve the performance measures of the system. © Springer International Publishing AG, part of Springer Nature 2018.

  • 359.
    Salman, Muhammad
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Collision Detection and Overtaking Using Artificial Potential Fields in Car Racing game TORCS using Multi-Agent based Architecture2013Independent thesis Advanced level (degree of Master (Two Years))Oppgave
    Abstract [en]

    The Car Racing competition platform is used for evaluating different car control solutions under competitive conditions [1]. These competitions are organized as part of the IEEE Congress on Evolutionary Computation (CEC) and Computational Intelligence and Games Sym-posium (CIG). The goal is to learn and develop a controller for a car in the TORCS open source racing game [2]. Oussama Khatib [3] (1986) introduced Artificial potential fields (APFs) for the first time while looking for new ways to avoid obstacles for manipulators and mobile robots in real time. In car racing games a novel combination of artificial potential fields as the major control paradigm for car controls in a multi-agent system is being used to coordinate control interests in different scenarios [1]. Here we extend the work of Uusitalo and Stefan J. Johansson by introducing effective collision detection, overtaking maneuvers, run time evaluation and detailed analysis of the track using the concept of multi-agent artificial potential fields MAPFs. The results of our extended car controller in terms of lap time, number of damages and position in the race is improved.

  • 360.
    SANA, VINEESHA
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Multipath TCP and Measuring endto-end TCP Throughput: Measuring TCP Metrics and ways to improve TCP Throughput performance2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Internet applications make use of the services provided by a transport protocol, such as TCP (a reliable, in-order stream protocol). We use the term Transport Service to mean the endtoend service provided to application by the transport layer. That service can only be provided correctly if information about the intended usage is supplied from the application. The application may determine this information at the design time, compile time, or run time, and it may include guidance on whether a feature is required, a preference by the application, or something in between. Multipath TCP (MPTCP) adds the capability of using multiple paths to a regular TCP session. Even though it is designed to be totally backward compatible to applications. The data transport differs compared to regular TCP, and there are several additional degrees of freedom that the particular application may want to exploit. Multipath TCP is particularly useful in the context of wireless networks using both Wi-Fi and a mobile network is a typical use case. In addition to the gains in throughput from inverse multiplexing, links may be added or dropped as the user moves in or out of coverage without disrupting the end-to-end TCP connection. The problem of link handover is thus solved by abstraction in the transport layer, without any special mechanisms at the network or link level.

    Handover functionality can then be implemented at the endpoints without requiring special functionality in the sub-networks according to the Internet's end-to-end principle. Multipath TCP can balance a single TCP connection across multiple interfaces and reach very high throughput.

  • 361.
    Sandgren, Per
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Security Assessment and *nix Package Vulnerabilities2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Background. Vulnerabilities in software provides attackers with the means to fulfill unlawful behavior. Since software has so much power, gaining control over vulnerabilities can mean that an attacker gains unauthorized powers. Since vulnerabilities are the keys that let attackers attack, vulnerabilities must be discovered and mitigated. Scanning vulnerable machines is not enough, and scanning data results must be parsed to prioritize vulnerability mitigation and conduct security assessment. Objectives. Creating a parser is the first objective, a tool that takes in input, filters it and gives output specified by the parser. The second objective is to have the parser connect found packages to known vulnerabilities. And the last objective is to have the parser give the output more information, sort them by severity and give information on what areas they are vulnerable. Methods. The interviews are conducted on experienced employees at Truesec AB. A parser is implemented with guidance from the supervisor at Truesec. The parser is experimented with to check practicality of parser. Results. The parser can find vulnerabilities from the Centos tests and does not find any from the Debian tests. From the interviews, we see that more information strengthens a security assessment. Expanding the scanning results will provide more information to the person(s) conducting security assessment. Conclusions. The amount of information gathered in security assessment needs to be expanded to make the assessment more reliable. Packages found can be connected with vulnerabilities by implementing a vulnerability database to match packages. The parser developed does not help in security assessment since the output is not reliable enough, this is caused by the phenomenon backporting.

  • 362.
    Santos, Rodrigo
    et al.
    Fed Univ State Rio de Janeiro, BRA.
    Teixeira, Eldanae
    Univ Fed Rio de Janeiro, BRA.
    Mendes, Emilia
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik. Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för programvaruteknik.
    McGregor, John
    Clemson Univ, USA.
    2nd Workshop on Social, Human, and Economic Aspects of Software (WASHES) Special Edition for Software Reuse2017Inngår i: MASTERING SCALE AND COMPLEXITY IN SOFTWARE REUSE (ICSR 2017) / [ed] Botterweck, G Werner, C, SPRINGER INTERNATIONAL PUBLISHING AG , 2017, s. 223-224Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The Special Edition for Software Reuse of the Workshop on Social, Human, and Economic Aspects of Software (WASHES) aims at bringing together researchers and practitioners who are interested in social, human, and economic aspects of software. WASHES is a forum to discuss models, methods, techniques, and tools to achieve software quality, improve reuse and deal with the existing issues in this context. This special edition's main topic is "Challenges of Reuse and the Social, Human, and Economic Aspects of Software". We believe it is important to investigate software reuse beyond the technical perspective and understand how the non-technical barriers of reuse affect practices, processes and tools in practice.

  • 363.
    Seethamraju, Arun Tej
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Attribute Based Encryption of Electronic Health Records: Comparative study of existing algorithms2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Cloud Computing today, is an evolving technology which features large Data Storage and ready-to-access from any device. The Healthcare Industry stores large Databases of patient’s records, considering the advantages of Cloud Computing it is looking forward to moving on from the traditional, proprietary Database Management Model into an Open Source Cloud DBMS Model. To complete this transition, it is of primary importance to provide Privacy and Security for Electronic Medical Record / Electronic Health Record. There are several kinds of research being done on how to mitigate these privacy issues using algorithms like Attribute Based Encryption and Identity-Based Encryption. In this study, we compare the performance of these two attribute based encryption methods. This thesis compares the performance of the state-of-the-art Attribute Based Encryption Schemas for Electronic Medical Record / Electronic Health Record Systems. Performance evaluation is conducted in local and cloud environments. A Literature Review has been performed to identify the existing Cloud-based Electronic Health Record Systems which uses the attribute based encryption as a mechanism to mitigate the privacy issues and realization in Cloud. Two algorithms have been selected by performing snowballing from the IEEE Research Articles. Experimentation was performed on the two algorithms in a local machine and on Amazon Web Services Cloud Platform to compare the performance. Verification of performance in each stage of the execution of the algorithms, in both local machine and Cloud environment, was done.

  • 364.
    Shafqat, Adnan
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Mobile Usability of Intelligent Electronic Devices2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Context: The Human Machine Interface (HMI) for Intelligent Electronic Devices (IEDs) is limited in its capability and is often the most common cause of failure when interacting with devices. A new approach to interact with these devices is needed with focus on improving interaction and effective visualization of information.

    Objectives: In this thesis, we investigate and propose a solution to visualize data of existing IED in interactive way. A mobile based prototype is proposed to list alarms, events and disturbances. Further single line diagram shown with capability to switch controls. Objective of proposed solution is to investigate specific use of mobile device from the perspective of usability and compare the new prototype with existing use of IED monochrome screen interface.

    Methods: Mixed approach based on qualitative and quantitative methods is conducted for analysis of the problem, method and approach to solve the problems in the domain of Substation automation. Analysis of the problem was carried out with the literature review of the technical documentation of IEDs. Experiments are performed in real environment to test and verify the usability of prototype.

    Results: Experiments results of proposed solution indicate that new approach is acceptable. The interfaces developed in mobile provide better results than traditional interfaces of IED. The difference between them is significant.

    Conclusions: We conclude that mobile usability gives better interaction, freedom, visualization of information and enhance the users’ experience by providing context specific information as compared to the existing Local Human Machine Interface of Intelligent Electronic Devices. The study provides strong results that recent developments of mobile technologies have revolutionized users’ possibilities to access information in an easy and better way.

  • 365.
    Shahid, Muhammad
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Shahzad, Raja Muhammad Khurram
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Selection of a Graduate Thesis Topic in a Multicultural Educational Environment2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This article presents a case study, performed at Blekinge Institute of Technology (BTH), Sweden, about the topic selection routines for a graduate thesis. The study focuses on the international graduate students who are having different academic cultures of their respective countries. Given that BTH has succeeded in the provision of an academic environment that has been efficient in absorbing different academic cultures in a productive manner at a reasonably good scale. However, in a multi-cultural educational environment, it is a challenge for most international students to adapt to the new academic culture and select the graduate thesis topic according to their real potential. Our findings gathered through an online survey, questionnaire, and focus group discussion is presented. The conclusions indicate, albeit, BTH has well defined routines for the thesis selection, the international graduate students face problems at the stage of thesis selection. The article concludes with suggestions to refine the thesis selection process at the micro level to help both students and staff.

  • 366.
    Shahzad, Raja Khurram
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Mehwish, Fatima
    Lavesson, Niklas
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Boldt, Martin
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Consensus decision making in random forests2015Inngår i: Revised Selected Papers of the First International Workshop on Machine Learning, Optimization, and Big Data, 2015, Vol. 9432, s. 347-358Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The applications of Random Forests, an ensemble learner, are investigated in different domains including malware classification. Random Forests uses the majority rule for the outcome, however, a decision from the majority rule faces different challenges such as the decision may not be representative or supported by all trees in Random Forests. To address such problems and increase accuracy in decisions, a consensus decision making (CDM) is suggested. The decision mechanism of Random Forests is replaced with the CDM. The updated Random Forests algorithm is evaluated mainly on malware data sets, and results are compared with unmodified Random Forests. The empirical results suggest that the proposed Random Forests, i.e., with CDM performs better than the original Random Forests.

  • 367.
    Shao, Borong
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    A Mixture-of-Experts Approach for Gene Regulatory Network Inference2014Independent thesis Advanced level (degree of Master (Two Years))Oppgave
    Abstract [en]

    Context. Gene regulatory network (GRN) inference is an important and challenging problem in bioinformatics. A variety of machine learning algorithms have been applied to increase the GRN inference accuracy. Ensemble learning methods are shown to yield a higher inference accuracy than individual algorithms. Objectives. We propose an ensemble GRN inference method, which is based on the principle of Mixture-of-Experts ensemble learning. The proposed method can quantitatively measure the accuracy of individual GRN inference algorithms at the network motifs level. Based on the accuracy of the individual algorithms at predicting different types of network motifs, weights are assigned to the individual algorithms so as to take advantages of their strengths and weaknesses. In this way, we can improve the accuracy of the ensemble prediction. Methods. The research methodology is controlled experiment. The independent variable is method. It has eight groups: five individual algorithms, the generic average ranking method used in the DREAM5 challenge, the proposed ensemble method including four types of network motifs and five types of network motifs. The dependent variable is GRN inference accuracy, measured by the area under the precision-recall curve (AUPR). The experiment has training and testing phases. In the training phase, we analyze the accuracy of five individual algorithms at the network motifs level to decide their weights. In the testing phase, the weights are used to combine predictions from the five individual algorithms to generate ensemble predictions. We compare the accuracy of the eight method groups on Escherichia coli microarray dataset using AUPR. Results. In the training phase, we obtain the AUPR values of the five individual algorithms at predicting each type of the network motifs. In the testing phase, we collect the AUPR values of the eight methods on predicting the GRN of the Escherichia coli microarray dataset. Each method group has a sample size of ten (ten AUPR values). Conclusions. Statistical tests on the experiment results show that the proposed method yields a significantly higher accuracy than the generic average ranking method. In addition, a new type of network motif is found in GRN, the inclusion of which can increase the accuracy of the proposed method significantly.

  • 368. Shao, Borong
    et al.
    Lavesson, Niklas
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Boeva, Veselka
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Shahzad, Raja Khurram
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    A mixture-of-experts approach for gene regulatory network inference2016Inngår i: INTERNATIONAL JOURNAL OF DATA MINING AND BIOINFORMATICS, ISSN 1748-5673, Vol. 14, nr 3, s. 258-275Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Gene regulatory network (GRN) inference is an important problem in bioinformatics. Many machine learning methods have been applied to increase the inference accuracy. Ensemble learning methods are shown in DREAM3 and DREAM5 challenges to yield a higher inference accuracy than individual algorithms. However, no ensemble method has been proposed to take advantage of the complementarity among existing algorithms from the perspective of network motifs. We propose an ensemble method based on the principle of Mixture-of-Experts ensemble learning. The method can quantitatively evaluate the accuracy of individual algorithms on predicting each type of the network motifs and assign weights to the algorithms accordingly. The individual predictions are then used to generate the ensemble prediction. By performing controlled experiments and statistical tests, the proposed ensemble method is shown to yield a significantly higher accuracy than the generic average ranking method used in the DREAM5 challenge. In addition, a new type of network motif is found in GRN, the inclusion of which can increase the accuracy of the proposed method significantly.

  • 369.
    Shirinbab, Sogand
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Performance Aspects in Virtualized Software Systems2014Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Virtualization has significantly improved hardware utilization by allowing IT service providers to create and run several independent virtual machine instances on the same physical hardware. One of the features of virtualization is live migration of the virtual machines while they are active, which requires transfer of memory and storage from the source to the destination during the migration process. This problem is gaining importance since one would like to provide dynamic load balancing in cloud systems where a large number of virtual machines share a number of physical servers. In order to reduce the need for copying files from one physical server to another during a live migration of a virtual machine, one would like all physical servers to share the same storage. Providing a physically shared storage to a relatively large number of physical servers can easily become a performance bottleneck and a single point of failure. This has been a difficult challenge for storage solution providers, and the state-of-the-art solution is to build a so called distributed storage system that provides a virtual shared disk to the outside world; internally a distributed storage system consists of a number of interconnected storage servers, thus avoiding the bottleneck and single point of failure problems. In this study, we have done a performance measurement on different distributed storage solutions and compared their performance during read/write/delete processes as well as their recovery time in case of a storage server going down. In addition, we have studied performance behaviors of various hypervisors and compare them with a base system in terms of application performance, resource consumption and latency. We have also measured the performance implications of changing the number of virtual CPUs, as well as the performance of different hypervisors during live migration in terms of downtime and total migration time. Real-time applications are also increasingly deployed in virtualized environments due to scalability and flexibility benefits. However, cloud computing research has not focused on solutions that provide real-time assurance for these applications in a way that also optimizes resource consumption in data centers. Here one of the critical issues is scheduling virtual machines that contain real-time applications in an efficient way without resulting in deadline misses for the applications inside the virtual machines. In this study, we have proposed an approach for scheduling real-time tasks with hard deadlines that are running inside virtual machines. In addition we have proposed an overhead model which considers the effects of overhead due to switching from one virtual machine to another.

  • 370.
    Shirinbab, Sogand
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Performance Implications of Virtualization2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Virtualization is a component of cloud computing. Virtualization transforms traditional inflexible, complex infrastructure of individual servers, storage, and network hardware into a flexible virtual resource pool and increases IT agility, flexibility, and scalability while creating significant cost savings. Additional benefits of virtualization include, greater work mobility, increased performance and availability of resources, and automated operations. Many virtualization solutions have been implemented. There are plenty of cloud providers using different virtualization solutions to provide virtual machines (VMs) and containers, respectively. Various virtualization solutions have different performance overheads due to their various implementations of virtualization and supported features. A cloud user should understand performance overheads of different virtualization solutions and the impact on the performance caused by different virtualization features, so that it can choose appropriate virtualization solution, for the services to avoid degrading their quality of services (QoSs). In this research, we investigate the impacts of different virtualization technologies such as, container-based, and hypervisor-based virtualization as well as various virtualization features such as, over-allocation of resources, live migration, scalability, and distributed resource scheduling on the performance of various applications for instance, Cassandra NoSQL database, and a large telecommunication application. According to our results, hypervisor-based virtualization has many advantages and is more mature compare to the recently introduced container-based virtualization. However, impacts of the hypervisorbased virtualization on the performance of the applications is much higher than the container-based virtualization as well as the non-virtualized solution. The findings of this research should be of benefit to the ones who provide planning, designing, and implementing of the IT infrastructure.

  • 371.
    Shirinbab, Sogand
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Performance Implications of Over-allocation of Virtual CPUs2015Inngår i: 2015 International Symposium on Networks, Computers and Communications (ISNCC 2015), IEEE , 2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A major advantage of cloud environments is that one can balance the load by migrating virtual machines (VMs) from one server to another. High performance and high resource utilization are also important in a cloud. We have observed that over-allocation of virtual CPUs to VMs (i.e. allocating more vCPUs to VMs than there CPU cores on the server) when there are many VMs running on one host can reduce performance. However, if we do not use any over-allocation of virtual CPUs we may suffer from poor resource utilization after VM migration. Thus, it is important to identify and quantify performance bottlenecks when running in virtualized environment. The results of this study will help virtualized environment service providers to decide how many virtual CPUs should be allocated to each VM.

  • 372.
    Shirinbab, Sogand
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Performance implications of resource over-allocation during the live migration2016Inngår i: 8TH IEEE INTERNATIONAL CONFERENCE ON CLOUD COMPUTING TECHNOLOGY AND SCIENCE (CLOUDCOM 2016), IEEE Computer Society, 2016, s. 552-557Konferansepaper (Fagfellevurdert)
    Abstract [en]

    As the number of cloud users are increasing, it becomes essential for cloud service providers to allocate the right amount of resources to virtual machines, especially during live migration. In order to increase the resource utilization and reduce waste, the providers have started to think about the role of over-allocating the resources. However, the benefits of over-allocations are not without inherent risks. In this paper, we conducted an experiment using a large telecommunication application that runs inside virtual machines, here we have varied the number of vCPU resources allocated to these virtual machines in order to find the best choice which at the same time reduces the risk of underallocating resources after the migration and increases the performance during the live migration. During our measurements we have used VMware's vMotion to migrate virtual machines while they are running. The results of this study will help virtualized environment service providers to decide how much resources should be allocated for better performance during live migration as well as how much resource would be required for a given load.

  • 373.
    Shirinbab, Sogand
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Scheduling Tasks with Hard Deadlines in CloudBased Virtualized Software SystemsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    There is scheduling on two levels in real-time applications executing in a virtualized environment: traditional real-time scheduling of the tasks in the realtime application, and scheduling of different Virtual Machines (VMs) on the hypervisor level. In this paper, we describe a technique for calculating a period and an execution time for a VM containing a real-time application with hard deadlines. This result makes it possible to apply existing real-time scheduling theory when scheduling VMs on the hypervisor level, thus making it possible to guarantee that the real-time tasks in a VM meet their deadlines. If overhead for switching from one VM to another is ignored, it turns out that (infinitely) short VM periods minimize the utilization that each VM needs to guarantee that all real-time tasks in that VM will meet their deadlines. Having infinitely short VM periods is clearly not realistic, and in order to provide more useful results we have considered a fixed overhead at the beginning of each execution of a VM. Considering this overhead, a set of real-time tasks, the speed of each processor core, and a certain processor utilization of the VM containing the real-time tasks, we present a simulation study and some performance bounds that make it possible to determine if it is possible to schedule the real-time tasks in the VM, and in that case for which periods of the VM that this is possible.

  • 374.
    Shirinbab, Sogand
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Scheduling Tasks with Hard Deadlines in CloudBased Virtualized Software SystemsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    There is scheduling on two levels in real-time applications executing in a virtualized environment: traditional real-time scheduling of the tasks in the realtime application, and scheduling of different Virtual Machines (VMs) on the hypervisor level. In this paper, we describe a technique for calculating a period and an execution time for a VM containing a real-time application with hard deadlines. This result makes it possible to apply existing real-time scheduling theory when scheduling VMs on the hypervisor level, thus making it possible to guarantee that the real-time tasks in a VM meet their deadlines. If overhead for switching from one VM to another is ignored, it turns out that (infinitely) short VM periods minimize the utilization that each VM needs to guarantee that all real-time tasks in that VM will meet their deadlines. Having infinitely short VM periods is clearly not realistic, and in order to provide more useful results we have considered a fixed overhead at the beginning of each execution of a VM. Considering this overhead, a set of real-time tasks, the speed of each processor core, and a certain processor utilization of the VM containing the real-time tasks, we present a simulation study and some performance bounds that make it possible to determine if it is possible to schedule the real-time tasks in the VM, and in that case for which periods of the VM that this is possible.

  • 375.
    Shirinbab, Sogand
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Scheduling Tasks with Hard Deadlines in Virtualized Software SystemsInngår i: Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is scheduling on two levels in real-time applications executing in a virtualized environment: traditional real-time scheduling of the tasks in the real-time application, and scheduling of different Virtual Machines (VMs) on the hypervisor level. In this paper, we describe a technique for calculating a period and an execution time for a VM containing a real-time application with hard deadlines. This result makes it possible to apply existing real-time scheduling theory when scheduling VMs on the hypervisor level, thus making it possible to guarantee that the real-time tasks in a VM meet their deadlines. If overhead for switching from one VM to another is ignored, it turns out that (infinitely) short VM periods minimize the utilization that each VM needs to guarantee that all real-time tasks in that VM will meet their deadlines. Having infinitely short VM periods is clearly not realistic, and in order to provide more useful results we have considered a fixed overhead at the beginning of each execution of a VM. Considering this overhead, a set of real-time tasks, the speed of  each processor core, and a certain processor utilization of the VM containing the real-time tasks, we present a simulation study and some performance bounds that make it possible to determine if it is possible to schedule the real-time tasks in the VM, and in that case for which periods of the VM that  is possible.

  • 376.
    Shirinbab, Sogand
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Casalicchio, Emiliano
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Performance Comparison between Horizontal Scaling of Hypervisor and Container Based Virtualization using Cassandra NoSQL Database2018Inngår i: Proceeding of the 3rd International Conference on Virtualization Application and Technology, 2018, , s. 6Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Cloud computing promises customers the ondemand ability to scale in face of workload variations. There are different ways to accomplish scaling, one is vertical scaling and the other is horizontal scaling. The vertical scaling refers to buying more power (CPU, RAM), buying a more expensive and robust server, which is less challenging to implement but exponentially expensive. While, the horizontal scaling refers to adding more servers with less processor and RAM, which is usually cheaper overall and can scale very well. The majority of cloud providers prefer the horizontal scaling approach, and for them would be very important to know about the advantages and disadvantages of both technologies from the perspective of the application performance at scale. In this paper, we compare performance differences caused by scaling of the different virtualization technologies in terms of CPU utilization, latency, and the number of transactions per second. The workload is Apache Cassandra, which is a leading NoSQL distributed database for Big Data platforms. Our results show that running multiple instances of the Cassandra database concurrently, affected the performance of read and write operations differently; for both VMware and Docker, the maximum number of read operations was reduced when we ran several instances concurrently, whereas the maximum number of write operations increased when we ran instances concurrently.

  • 377.
    Shirinbab, Sogand
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Casalicchio, Emiliano
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Performance Evaluation of Container and Virtual Machine Running Cassandra Workload2017Inngår i: PROCEEDINGS OF 2017 3RD INTERNATIONAL CONFERENCE OF CLOUD COMPUTING TECHNOLOGIES AND APPLICATIONS (CLOUDTECH) / [ed] Essaaidi, M Zbakh, M, 2017, s. 24-31Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Today, scalable and high-available NoSQL distributed databases are largely used as Big Data platforms. Such distributed databases typically run on a virtualized infrastructure that could be implemented using Hypervisorb ased virtualiz ation or Container-based virtualiz ation. Hypervisor-based virtualization is a mature technology but imposes overhead on CPU, memory, networking, and disk Recently, by sharing the operating system resources and simplifying the deployment of applications, container-based virtualization is getting more popular. Container-based virtualization is lightweight in resource consumption while also providing isolation. However, disadvantages are security issues and 110 performance. As a result, today these two technologies are competing to provide virtual instances for running big data platforms. Hence, a key issue becomes the assessment of the performance of those virtualization technologies while running distributed databases. This paper presents an extensive performance comparison between VMware and Docker container, while running Apache Cassandra as workload. Apache Cassandra is a leading NoSQL distributed database when it comes to Big Data platforms. As baseline for comparisons we used the Cassandra's performance when running on a physical infrastructure. Our study shows that Docker had lower overhead compared to the VMware when running Cassandra. In fact, the Cassandra's performance on the Dockerized infrastructure was as good as on the Non-Virtualized.

  • 378.
    Shirinbab, Sogand
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Håkansson, Jim
    Ericsson AB, SWE.
    Comparing Automatic Load Balancing using VMware DRS with a Human Expert2016Inngår i: 2016 IEEE INTERNATIONAL CONFERENCE ON CLOUD ENGINEERING WORKSHOP (IC2EW), IEEE, 2016, s. 239-246Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In recent years, there has been a rapid growth of interest in dynamic management of resources in virtualized systems. Virtualization provides great flexibility in terms of resource sharing but at the same time it also brings new challenges for load balancing using automatic migrations of virtual machines. In this paper, we have evaluated VMware's Distributed Resource Scheduler (DRS) in a number of realistic scenarios using multiple instances of a large industrial telecommunication application. We have measured the performance on the hosts before and after the migration in terms of CPU utilization, and compared DRS migrations with human expert migrations. According to our results, DRS with the most aggressive threshold gave us the best results. It could balance the load in 40% of cases while in other cases it could not balance the load properly. DRS did completely unnecessary migrations back and forth in some cases.

  • 379.
    Shirinbab, Sogand
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Ilie, Dragos
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Performance Comparison of KVM, VMware and XenServer using a Large Telecommunication Application2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    One of the most important technologies in cloud computing is virtualization. This paper presents the results from a performance comparison of three well-known virtualization hypervisors: KVM, VMware and XenServer. In this study, we measure performance in terms of CPU utilization, disk utilization and response time of a large industrial real-time application. The application is running inside a virtual machine (VM) controlled by the KVM, VMware and XenServer hypervisors, respectively. Furthermore, we compare the three hypervisors based on downtime and total migration time during live migration. The results show that the Xen hypervisor results in higher CPU utilization and thus also lower maximum performance compared to VMware and KVM. However, VMware causes more write operations to disk than KVM and Xen, and Xen causes less downtime than KVM and VMware during live migration. This means that no single hypervisor has the best performance for all aspects considered here.

  • 380.
    Sidorova, Yulia
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Garcia, J.
    Bridging from syntactic to statistical methods: Classification with automatically segmented features from sequences2015Inngår i: Pattern Recognition, ISSN 0031-3203, E-ISSN 1873-5142, Vol. 48, nr 11, s. 3749-3756Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To integrate the benefits of statistical methods into syntactic pattern recognition, a Bridging Approach is proposed: (i) acquisition of a grammar per recognition class; (ii) comparison of the obtained grammars in order to find substructures of interest represented as sequences of terminal and/or non-terminal symbols and filling the feature vector with their counts; (iii) hierarchical feature selection and hierarchical classification, deducing and accounting for the domain taxonomy. The bridging approach has the benefits of syntactic methods: preserves structural relations and gives insights into the problem. Yet, it does not imply distance calculations and, thus, saves a non-trivial task-dependent design step. Instead it relies on statistical classification from many features. Our experiments concern a difficult problem of chemical toxicity prediction. The code and the data set are open-source. (C) 2015 Elsevier Ltd. All rights reserved.

  • 381.
    Sidorova, Yulia
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Rosander, Oliver
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Grahn, Håkan
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Skold, Lars
    telenor, SWE.
    Recommendations for marketing campaigns in telecommunication business based on the footprint analysis: Who is a good client?2017Inngår i: 2017 8th International Conference on Information, Intelligence, Systems and Applications, IISA 2017, Institute of Electrical and Electronics Engineers Inc. , 2017, s. 513-518Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A major investment made by a telecom operator goes into the infrastructure and its maintenance, while business revenues depend on how efficiently it is exploited. We present a data-driven analytic strategy based on combinatorial optimization and analysis of historical data. The data cover historical mobility in one region of Sweden during a week. Applying the proposed method in a case study, we have identified the optimal combination of geodemographic segments in the customer base, developed a functionality to assess the potential of a planned marketing campaign, and investigated how many and which segments to target for customer base growth. A comprehensible summary of the conclusions is created via execution of the queries with a fuzzy logic component. © 2017 IEEE.

  • 382.
    Sidorova, Yulia
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Rosander, Oliver
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Sköld, Lars
    Telenor, SWE.
    Grahn, Håkan
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Finding a healthy equilibrium of geo-demographic segments for a telecom business: Who are malicious hot-spotters?2019Inngår i: Machine Learning Paradigms: Advances in Data Analytics / [ed] George A. Tsihrintzis, Dionisios N. Sotiropoulos, Lakhmi C. Jain, Springer Science and Business Media Deutschland GmbH , 2019, s. 187-196Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    In telecommunication business, a major investment goes into the infrastructure and its maintenance, while business revenues are proportional to how big, good, and well-balanced the customer base is. In our previous work we presented a data-driven analytic strategy based on combinatorial optimization and analysis of the historical mobility designed to quantify the desirability of different geo-demographic segments, and several segments were recommended for a partial reduction. Within a segment, clients are different. In order to enable intelligent reduction, we introduce the term infrastructure-stressing client and, using the proposed method, we reveal the list of the IDs of such clients. We also have developed a visualization tool to allow for manual checks: it shows how the client moved through a sequence of hot spots and was repeatedly served by critically loaded antennas. The code and the footprint matrix are available on the SourceForge. © 2019, Springer International Publishing AG, part of Springer Nature.

  • 383.
    Sidorova, Yulia
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Sköld, Lars
    Telenor, SWE.
    Lennerstad, Håkan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för matematik och naturvetenskap.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    The Use of Fuzzy Logic in Creating a Visual Data Summary of a Telecom Operator’s Customer Base2019Inngår i: Communications in Computer and Information Science, Springer Verlag , 2019, Vol. 932, s. 301-312Konferansepaper (Fagfellevurdert)
    Abstract [en]

    As pointed out by Zadeh, the mission of fuzzy logic in the era of big data is to create a relevant summary of huge amounts of data and facilitate decision-making. In this study, elements of fuzzy set theory are used to create a visual summary of telecom data, which gives a comprehensive idea concerning the desirability of boosting an operator’s presence in different neighborhoods and regions. The data used for validation cover historical mobility in a region of Sweden during a week. Fuzzy logic allows us to model inherently relative characteristics, such as “a tall man” or “a beautiful woman”, and importantly it also defines “anchors”, the situations (characterized with the value of the membership function for the characteristic) under which the relative notion receives a unique crisp interpretation. We propose color coding of the membership value for the relative notions such as “the desirability of boosting operator’s presence in the neighborhood” and “how well the operator is doing in the region”. The corresponding regions on the map (e.g., postcode zones or larger groupings) are colored in different shades passing from green (1) though yellow (0.5) to red (0). The color hues pass a clear intuitive message making the summary easy to grasp. © 2019, Springer Nature Singapore Pte Ltd.

  • 384.
    Sidorova, Yulia
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Sköld, Lars
    Telenor Sverige AB, SWE.
    Rosander, Oliver
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Optimizing utilization in cellular radio networks using mobility data2019Inngår i: Optimization and Engineering, ISSN 1389-4420, E-ISSN 1573-2924, Vol. 20, nr 1, s. 37-64Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The main resource for any telecom operator is the physical radio cell network. We present two related methods for optimizing utilization in radio networks: Tetris optimization and selective cell expansion. Tetris optimization tries to find the mix of users from different market segments that provides the most even load in the network. Selective cell expansion identifies hotspot cells, expands the capacity of these radio cells, and calculates how many subscribers the radio network can handle after the expansions. Both methods are based on linear programming and use mobility data, i.e., data defining where different categories of subscribers tend to be during different times of the week. Based on real-world mobility data from a region in Sweden, we show that Tetris optimization based on six user segments made it possible to increase the number of subscribers by 58% without upgrading the physical infrastructure. The same data show that by selectively expanding less than 6% of the cells we are able to increase the number of subscribers by more than a factor of three without overloading the network. We also investigate the best way to combine Tetris optimization and selective cell expansion. © 2018 The Author(s)

  • 385.
    Sigakova, Ksenia
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Mbiydzenyuy, Gideon
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Holmgren, Johan
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Impacts of traffic conditions on the performance of road freight transport2015Inngår i: 2015 IEEE 18TH INTERNATIONAL CONFERENCE ON INTELLIGENT TRANSPORTATION SYSTEMS, 2015, s. 2947-2952Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The efficiency of road transport is typically influenced by factors such as, weather, choice of road, and time of day, and day of the week. Knowledge about interactions between different traffic-and transport related factors and their influence on the execution of transport is important in transport planning. The purpose of this paper is to study the impact of different factors on the performance of road transport. We aim to contribute to improved transport planning by analysing traffic and transport data obtained from different sources in order to support data driven decision making. Through a review of existing literature and discussions with a Swedish road transport operator, we identified factors that could be relevant to consider when planning a transport, e.g., related to weather, location of roads where the transport will take place, and planned time of the transport. As a result of variation in size, type and volume of the data representing these factors, suitable machine learning algorithms were selected, such as Decision Stump, M5 model tree, M5 regression tree, RepTree, M5 rules, and linear regression in order to study the data. Our experimental results illustrate the complexity associated to the performance of road transport systems mainly because of the dependency between the choices of influencing factors and geographic location of the road segment.

  • 386.
    Sigurdsson, Victoria
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Untangling the Web: Finding Your Forgotten Assets2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Background. In the years between 2016 and 2017, the number of attacks against web application increased by approximately 21.89 percent. The total recorded amount of incidents during 2017 was 6,502. To assure security, patching and scanning are required. This assumes that the company is aware of all their external facing web applications. The company Outpost24 is observing an increased request for a solution capable of finding all external web application owned by one company.

    Objectives. This thesis study six methods to identify assets owned by one company. The methods are classified into weak and strong indicators. Based on the classifications, two algorithms are developed. The algorithms are executed against two companies, Outpost24 and Company A. The objective is to evaluate the six methods and decide if the methods are suitable for retrieving assets owned by one company.

    Methods. This study includes two experiments testing the two algorithms on two different companies. The experiments focus on to retrieve assets and data to make a decision upon the ownership of the assets. The observed data from the experiments are compared against data known by the two companies to verify if any data is unknown to the company prior to the experiment.

    Results. The results show that the identified methods are suitable for both identify assets and to decide upon ownership. Furthermore, assets not previously known was possible to identify. The results from the two methods are visualized as two node maps, providing an overview of identified assets. 

    Conclusions. It was concluded that there are methods that are useful when extracting assets from one given assets, and there are methods useful for extracting data used when deciding upon the owner. The methods will assist companies in raising their own awareness of their external facing assets, and in some cases identify assets which were previously unknown to them.

  • 387.
    Sokol, Maciej
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Ernstsson, Joakim
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Dynamic Heuristic Analysis Tool for Detection of Unknown Malware2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Context: In today's society virus makers have a large set of obfuscation tools to avoid classic signature detection used by antivirus software. Therefore there is a need to identify new and obfuscated viruses in a better way. One option is to look at the behaviour of a program by executing the program in a virtual environment to determine if it is malicious or benign. This approach is called dynamic heuristic analysis.

    Objectives: In this study a new heuristic dynamic analysis tool for detecting unknown malware is proposed. The proposed implementation is evaluated against state-of-the-art in terms of accuracy.

    Methods: The proposed implementation uses Cuckoo sandbox to collect the behavior of a software and a decision tree to classify the software as either malicious or benign. In addition, the implementation contains several custom programs to handle the interaction between the components.

    Results: The experiment evaluating the implementation shows that an accuracy of 90% has been reached which is higher than 2 out of 3 state-of-the-art software.

    Conclusions: We conclude that an implementation using Cuckoo and decision tree works well for classifying malware and that the proposed implementation has a high accuracy that could be increased in the future by including more samples in the training set.

  • 388. Soomro, Arjumand Bano
    et al.
    Salleh, Norsaremah
    Mendes, Emilia
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Grundy, John
    Burch, Giles
    Nordin, Azlin
    The effect of software engineers' personality traits on team climate and performance: A Systematic Literature Review2016Inngår i: Information and Software Technology, ISSN 0950-5849, E-ISSN 1873-6025, Vol. 73, s. 52-65Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Context: Over the past 50 years numerous studies have investigated the possible effect that software engineers' personalities may have upon their individual tasks and teamwork. These have led to an improved understanding of that relationship; however, the analysis of personality traits and their impact on the software development process is still an area under investigation and debate. Further, other than personality traits, "team climate" is also another factor that has also been investigated given its relationship with software teams' performance. Objective: The aim of this paper is to investigate how software professionals' personality is associated with team climate and team performance. Method: In this paper we detail a Systematic Literature Review (SLR) of the effect of software engineers' personality traits and team climate on software team performance. Results: Our main findings include 35 primary studies that have addressed the relationship between personality and team performance without considering team climate. The findings showed that team climate comprises a wide range of factors that fall within the fields of management and behavioral sciences. Most of the studies used undergraduate students as subjects and as surrogates of software professionals. Conclusions: The findings from this SLR would be beneficial for understanding the personality assessment of software development team members by revealing the traits of personality taxonomy, along with the measurement of the software development team working environment. These measurements would be useful in examining the success and failure possibilities of software projects in development processes. General terms: Human factors, performance. (C) 2016 Elsevier B.V. All rights reserved.

  • 389.
    Sreenibha Reddy, Byreddy
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Performance Metrics Analysis of GamingAnywhere with GPU accelerated NVIDIA CUDA2018Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The modern world has opened the gates to a lot of advancements in cloud computing, particularly in the field of Cloud Gaming. The most recent development made in this area is the open-source cloud gaming system called GamingAnywhere.

    The relationship between the CPU and GPU is what is the main object of our concentration in this thesis paper. The Graphical Processing Unit (GPU) performance plays a vital role in analyzing the playing experience and enhancement of GamingAnywhere. In this paper, the virtualization of the GPU has been concentrated on and is suggested that the acceleration of this unit using NVIDIA CUDA, is the key for better performance while using GamingAnywhere. After vast research, the technique employed for NVIDIA CUDA has been chosen as gVirtuS.

    There is an experimental study conducted to evaluate the feasibility and performance of GPU solutions by VMware in cloud gaming scenarios given by GamingAnywhere. Performance is measured in terms of bitrate, packet loss, jitter and frame rate. Different resolutions of the game are considered in our empirical research and our results show that the frame rate and bitrate have increased with different resolutions, and the usage of NVIDIA CUDA enhanced GPU.

  • 390.
    Srinadhuni, Siddhartha
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Performance Evaluation of Cassandra Scalability on Amazon EC22018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Context In the fields of communication systems and computer science, Infrastructure as a Service consists of building blocks for cloud computing and to provide robust network features. AWS is one such infrastructure as a service which provides several services out of which Elastic Cloud Compute (EC2) is used to deploy virtual machines across several data centers and provides fault tolerant storage for applications across the cloud. Apache Cassandra is one of the many NoSQL databases which provides fault tolerance and elasticity across the servers. It has a ring structure which helps the communication effective between the nodes in a cluster. Cassandra is robust which means that there will not be a down-time when adding new Cassandra nodes to the existing cluster.  Objectives. In this study quantifying the latency in adding Cassandra nodes to the Amazon EC2 instances and assessing the impact of Replication factors (RF) and Consistency Levels (CL) on autoscaling have been put forth. Methods. Primarily a literature review is conducted on how the experiment with the above-mentioned constraints can be carried out. Further an experimentation is conducted to address the latency and the effects of autoscaling. A 3-node Cassandra cluster runs on Amazon EC2 with Ubuntu 14.04 LTS as the operating system. A threshold value is identified for each Cassandra specific configuration and is scaled over to five nodes on AWS utilizing the benchmarking tool, Cassandra stress tool. This procedure is repeated for a 5-node Cassandra cluster and each of the configurations with a mixed workload of equal reads and writes. Results. Latency has been identified in adding Cassandra nodes on Amazon EC2 instances and the impacts of replication factors and consistency levels on autoscaling have been quantified. Conclusions. It is concluded that there is a decrease in latency after autoscaling for all the configurations of Cassandra and changing the replication factors and consistency levels have also resulted in performance change of Cassandra.

  • 391.
    Srinivas, Sri Krishna
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    On Added Value of Layer 4 ControlInformation for QoE Estimations2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Background: In the recent years, the focus of research has shifted to Quality of Experience(QoE) to maintain the user satisfaction levels and fulfill their expectations of the serviceoffered. Numerous work has been established in finding the relationship between the networklayer and QoE. But, it is fact that the transport layer is much closer to the end-user than thenetwork layer in the TCP/IP communication protocol suite. Thus, any changes in the degreeof satisfaction or degree of annoyance are directly reflected onto transport layer than on thenetwork layer. So, it becomes more significant to study the behavior of user satisfaction inrelation to transport layer than the network layer.

    Objectives: This research is to relate the behavior of TCP to QoE. The main considerations tobridge the gap between them are: (a) Analyzing the effects of using different versions of TCPon server and client side, (b) Monitoring and analyzing the intensity of TCP traffic in thereverse direction and (c) Investigating TCP control flags from client to server.

    Methods: QoE related parameters used in this research are: (a) Quality of video i.e., MOS, (b)Degree of disturbance caused by initial delay, (c) Degree of disturbance caused by jerkinessand (d) Degree of disturbance caused by freezes. Effects of network impairments like delay,jitter and packet loss are considered in this research. NetEm is used as the traffic emulationsoftware to shape the traffic. The packet capture analysis of traffic exchange is implementedusing tcpdump.

    Results and Conclusions: The aim of this research is to provide a passive-estimation methodto assess the user perceived performance. The results of this research provide valuablecontribution to service providers/operators to note the early warning signals from TCP reversetraffic to evaluate the decrease of user satisfaction level and try to cope or/and recover fromimpairments in the network. This research also provides a scope for future researchers toinvestigate other protocols both in transport and application layers.

  • 392.
    Stensmar, Isak
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Steganografi i bilder: En studie om bildformat och visuella bildrepresentationens påverkan vid lagring av data med hjälp av en steganografisk metod2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Sammanhang. Genom att använda steganografi i bilder är det möjligt att lagra en stor mängd data utan att påverka bilden som information lagras i. En vanlig metod som används inom steganografi är LSB (Least Significant Bit), som ofta anses vara en av de första metoderna som användes inom steganografi. Förutom valet av metod har personen ett val att göra när hen ska välja en bild som ska representera bärare av information. Vad man ofta försöker åstadkomma är att skapa en komplex metod men glömmer bort bilden som ska användas som bärare. I slutändan är det bilden som kommer att användas och testas vid olika mätningar.

    Mål. Den här studien kommer att undersöka om olika typer av bildformat, BMP, PNG, JPEG och TIFF, har någon påverkan när jämförelse görs av originalbilden och den modifierade, givet att en steganografisk metod används för att lagra informationen. Studien kommer även att undersöka om bildrepresentationen har någon påverkan på mätningarna.

    Metod. En utbyggd metod av Least Significant Bit metoden kommer att implementeras och användas för att lagra information i olika typer av bilder med olika bildformat. Ett experiment sätts upp för att undersöka formaten med hjälp av mätningsverktygen MSE (Mean Squared Error), PSNR (Peek Signal-to-Noise Ratio) och SSIM (Structural Similarity).

    Resultat. Vid jämförelse av de grafer och tabeller som togs fram, sågs JPEG ha ett bättre resultat genom att ha ett lägre differentiellt värde mellan varje test. BMP, PNG och TIFF hade minimala skillnader mellan varandra för varje test. För bildrepresentationen visade två bilder högre differentiellt värde än de resterande tre.

    Sammanfattning. Resultaten från experimentet visade att vilken komprimeringsmetod som ett bildformat använder kommer ha påverkan på mätningsvärdena. Resultaten visade också att bildrepresentation kan ha en påverkan på mätningarna av en bild men mer data behövs för att dra en slutsats. 

  • 393.
    Stezenbach, David
    et al.
    University of Vienna, AUT.
    Tutschku, Kurt Tutschku
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    A Performance Evaluation Metric for NFV Elements on Multiple Timescales2013Inngår i: Proceeding of the Global Communications Conference 2013 (GLOBECOM 2013)., 2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Todays virtualization technologies are manifold and a comparison is hardly achievable. Thus, a metric independent from the virtualization technology is required to compare different systems. The metric is measurable in a passive way, hence, no artificial traffic has to be generated, and the virtualization system needs not to be modified. It evaluates the throughput of events on different time slices. This methodology, in contrast to existing jitter evaluations, enables the identification of critical timescales in the virtualization system. In this demonstration a proof-of-concept for a performance metric for NFV elements on multiple timescales is presented. In a reduced environment consisting of a single virtual router host the influences of hardware resource sharing and other impact factors (e.g. cpu, memory or disc load) are made visible. The demonstration gives an example of a performance degrease on smaller timescales, which can not be identified by a common throughput measurement over time. Thus, the presented metric enables to identify critical system conditions and can be used to optimize the scheduling of NFV, to compare different virtualization technologies, or to grade the performance for specific applications.

  • 394.
    Strågefors, Linnea
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Undersökning av processorprestanda under arbetsbelastning2014Oppgave
    Abstract [sv]

    This thesis is an exploration of how a laptop system performance is affected by workload on the processor. The workload is represented by a process thread that is time consuming for the CPU and keeps the CPU continuously occupied with jobs. The load can be increased by adding more loading threads. The changes in the performance is measured by, for example, the processor utilisation, response time, priorities and temperature. The processor’s utilisation is affecting the system performance by how the processor is organising and distributing tasks. Increased workload require system methods that correspond to the load in order to maintain a certain system standard. Measuring the assigned thread priority numbers gives a more specific indication of which techniques the scheduler is using to handle the tasks. The response time characterises the impact of the workload relative time. It is investigated by timing the response of a system call, during an increasing workload of threads. The results illustrate an increasing growth of the response time, where a relative small added workload makes the system call about impractical to carry through at a particular load limit. The processor’s temperature and energy consumption entail changes in the system performance mainly in terms of the quality of the component, operationally and materially. It has also long-term effects on the surrounding components of the processor and on environmental issues.

  • 395.
    Svenhag, Olle
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Utvärdering av temporala analysmetoder inom brottskategorin bostadsinbrott2015Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Context. In year 2013 the number of reported residential burglariesin Sweden was 21000, where only 4-5 percent of those actuallygot solved [1]. The Swedish police is trying to improve their way ofworking to increase the number of solved burglaries, this by structuringthe data collection and analysing with computer science methods.Temporal analysis is the key to gure out when crime actually takesplace.

    Objectives. This thesis study ve dierent methods for analysingthe temporal data of residential burglaries. The temporal analysis isperformed on three time spans: time of day, day of the week and dayof the month. The objective is to evaluate the ve methods in thethree time spans and decide which method is the most suitable foreach of them.

    Methods. This study includes three experiments testing all ve methodson the three time spans. The experiments focus on comparing theobserved data against the data of burglaries with a known specictime of the crime. In order to test the performance of each method aChi-squared goodness-of-t test was used, as well as a visual comparisonof the produced plots.

    Results. The results showed that the Aoristic-method was the mostsuitable method to use when analysing temporal data of residentialburglars, if looking at the time of day, day of the week and day ofthe month. Using the methods we also generated plots of the threetemporal distributions, with an R script.

    Conclusions. We concluded that using the Aoristic-method is themost suitable method to use to generate plots from the temporal data.We also concluded that using this script with the Aoristic-method togenerate plots, would make it possible for the police to resource allocationaccording to when burglaries actually take place.

  • 396.
    Svensson, Benjamin
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Varnai, Kristian
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Servicing a Connected Car Service2015Oppgave
    Abstract [en]

    Increased wireless connectivity to vehicles invites both existing and new digital methods of attack, requiring the high prioritisation of security throughout the development of not just the vehicle, but also the services provided for it. This report examines such a connected car service used by thousands of customers every day and evaluates it from a security standpoint. The methods used for this evaluation include both direct testing of vulnerabilities, as well as the examination of design choices made which more broadly affect the system as a whole. With the results are included suggestions for solutions where necessary, and in the conclusion, design pitfalls and general considerations for system development are discussed.

  • 397.
    Tejaswi, Nunna
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Performance Analysis on Hybrid and ExactMethods for Solving Clustered VRP: A Comparative Study on VRP Algorithms2017Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Context: The Vehicle Routing Problem is an NP-hard problem with a combination of varieties oftopics like logistics, optimization research and data mining. There is a vast need of vehicle routingsolutions in day to day like with different constraints. According to the requirements, this problem hasbeen a field of interest to a lot of researchers who incorporate scientific methods to combine andinnovate new solutions to optimize the routing. Being an np-hard problem, it is almost impossible tocompute the solutions to optimality but years of research on this area has paid off quite significantlyand the solutions are optimized little by little and better than before. Some applications may or maynot find slight difference in the performance as a considerable affect but some applications orscenarios heavily depend on the performance of the solution where it is very vital that the solution isoptimized to the fullest. As a data mining technique clustering has been used very prominently in caseof portioning scenarios and similarly it has also began to surface in implementing VRP solutions.Although it has recently emerged into the Vehicle Routing era and shown some significant results, ithas not yet come into an open state or awareness. The awareness regarding clustering matters in ahuge extent to be considered by most of the recent researchers who formulate new algorithms to solveVRP and help them further optimize their solution.

    Objectives: In this study the significance of clustering has been considered to find out how the usageof clustering techniques can alter the performance of VRP based solutions favorably. Then to test theresults of two recently proposed cluster based algorithms, a comparison has been made to other typesof algorithms which prove how the algorithms stand with various methods.

    Methods: A literature review is performed using various articles that have been gathered from GoogleScholar and then an empirical experiment was conducted on the results available in the papers. Thisexperiment was done by performing a comparative analysis.

    Results: For the literature review the results were gathered from all the articles based on theirresearch, experience, use of clustering and how their result was improved by using clustering methodsin their formulations. Considering the experiment, the results of both the algorithm were comparedwith the results of five other papers who aim to solve the VRP using exactly the same instances thatwere used in the two algorithms in order to compare valid results on the same variables. Then theresults were analyzed for the purpose of comparison and conclusions were drawn accordingly.

    Conclusions: From the research performed in this paper we can conclude the vast significance ofclustering techniques that were drawn based on practical test results of various authors. From theexperiment performed it is clear that the Hybrid algorithm has a much higher performance than anyother algorithm it has been compared to. This algorithm has also been proven to enhance itsperformance due to the implementation of clustering techniques in their formulation. Since the resultswere only based on performance that is, in this case the total distance of the final route, future studyindicates the implementation of algorithms to compare them on basis of time complexity and spacecomplexity as well.

  • 398.
    Tillman, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Complex Transformative Portal Interaction2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Context. A portal in computer graphics is an opening which connects two spaces together. Portals can be used for occlusion culling for indoor environments or wormhole-like effects. This thesis address the latter and focus on how objects interact with such portals.

    Objectives. The objectives are to provide a solution to how objects can interact with complex portals in real-time with focus on visual (and physical) correctness and also present a background to how simple and complex portals work.

    Methods. A hybrid approach of a geometry and image technique is used to render portals. Intersection techniques and a technique related to constructive solid geometry is used to solve object-portal interactions. The research methodology used is implementation and simple analysis of the results is performed.

    Results. The results show that the implementation of the object-portal interaction scales exponentially. In the worst case it has a complexity of O(n² * m²) where n and m are the number of triangles in the object and portal respectively. Increasing the number of triangles in the object shape is more costly than increasing the number of triangles in the portal shape by the same amount. The results were not compared to previous knowledge as no results have been published of other object-portal interaction methods. The rendering of portals scales linearly with the number of triangles used to represent it.

    Conclusions. This thesis extends the state-of-the-art portal rendering system and adds a solution to object-portal interaction of complex shapes. It also provides a detailed background into the fundamentals of portals and their nature. The thesis is of interest to those who want object-portal interaction of both simple and complex portals used in gameplay and special effects without restriction on portal placement and shape, with the exception that portals may not have holes in their shape in the direction an intersecting object is moving.

  • 399.
    Trusz, Jakob
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Content Management Systems and MD5: Investigating Alternative Methods of Version Identification for Open Source Projects2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    WordPress is a very widely used content management system that enables users to easier create websites. The popularity of WordPress has made it a prime target for attacks by hackers since a potential vulnerability would affect many targets. Vulnerabilities that can be utilised in an attack are referred to as exploits. Most exploits are only viable for a subset of all the version of the software that they target. The knowledge of which version of a content managements system a website is running is often not explicit or easy to determine. Attackers can potentially exploit a vulnerable website faster if the version is known, since this allows them to search for existing vulnerabilities and exploits, instead of trying to identify a new vulnerability.

    The purpose of this thesis is to investigate existing and alternate methods for detecting the version of WordPress on websites that are powered by it. The scope is limited to an analysis of existing tools and the suggested methods for version identification are limited to identification using unique values that are calculated from the contents of files. The suggested methods for version identification and the generation of the required data is implemented using Python 3, the programming language. We investigate the feasibility of version obfuscation, how discernible a version of WordPress is, and how to compare versions of WordPress.

    The thesis has proven the feasibility of version identification with a new perspective that delivers more accurate results than previous methods. Version obfuscation has also been proven to be very feasible without affecting the usability of the WordPress website. Furthermore, a method for discerning between two specific versions of WordPress is presented. All the results are in theory applicable to other software projects that are hosted and developed in the same way. This new area of research has much for security professionals and has room for future improvement.

  • 400.
    Tummala, Akhil
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Self-learning algorithms applied in Continuous Integration system2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Context: Continuous Integration (CI) is a software development practice where a developer integrates a code into the shared repository. And, then an automated system verifies the code and runs automated test cases to find integration error. For this research, Ericsson’s CI system is used. The tests that are performed in CI are regression tests. Based on the time scopes, the regression test suites are categorized into hourly and daily test suits. The hourly test is performed on all the commits made in a day, whereas the daily test is performed at night on the latest build that passed the hourly test. Here, the hourly and daily test suites are static, and the hourly test suite is a subset of the daily test suite. Since the daily test is performed at the end of the day, the results are obtained on the next day, which is delaying the feedback to the developers regarding the integration errors. To mitigate this problem, research is performed to find the possibility of creating a learning model and integrating into the CI system, which can then create a dynamic hourly test suite for faster feedback.

    Objectives: This research aims to find the suitable machine learning algorithm for CI system and investigate the feasibility of creating self-learning test machinery. This goal is achieved by examining the CI system and, finding out what type data is required for creating the learning model for prioritizing the test cases. Once the necessary data is obtained, then the selected algorithms are evaluated to find the suitable learning algorithm for creating self-learning test machinery. And then, the investigation is done whether the created learning model can be integrated into the CI workflow to create the self-learning test machinery.

    Methods: In this research, an experiment is conducted for evaluating the learning algorithms. For this experimentation, the data is provided by Ericsson AB, Gothenburg. The dataset consists of the daily test information and the test case results. The algorithms that are evaluated in this experiment are Naïve Bayes, Support vector machines, and Decision trees. This evaluation is done by performing leave-one-out cross-validation. And, the learning algorithm performance is calculated by using the prediction accuracy. After obtaining the accuracies, the algorithms are compared to find the suitable machine learning algorithm for CI system.

    Results: Based on the Experiment results it is found that support vector machines have outperformed Naïve Bayes and Decision tree algorithms in performance. But, due to the challenges present in the current CI system, the created learning model is not feasible to integrate into the CI. The primary challenge faced by the CI system is, mapping of test case failure to its respective commit is no possible (cannot find which commit made the test case to fail). This is because the daily test is performed on the latest build which is the combination of commits made in that day. Another challenge present is low data storage. Due to this low data storage, problems like the curse of dimensionality and class imbalance has occurred.

    Conclusions: By conducting this research, a suitable learning algorithm is identified for creating a self-learning machinery. And, also identified the challenges facing to integrate the model in CI. Based on the results obtained from the experiment, it is recognized that support vector machines have high prediction accuracy in test case result classification compared to Naïve Bayes and Decision trees.

56789 351 - 400 of 435
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf