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  • 1.
    Ahmed, Olfet
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Saman, Nawar
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Utvärdering av nätverkssäkerheten på J Bil AB2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of this project is to evaluate the network security at J Bil AB. The focus will be on both social and technical issues. For the employees to be able to con-nect to remote servers and external services and perform their daily work tasks, secure connections is needed. J Bil Ab has no IT manager who actively maintains and monitors the network; rather they consult a computer company when changes and implementations are required. The projects’ goal is to identify gaps, come up with suggestions for improvement and to some extent implement so-lutions. To do this, an observation of the employees hav been made, an inter-view have been held, and several attacks on the network have been performed. Based on the data collected, it was concluded that the company has shortcom-ings in IT security. Above all, the social security appeared to have major gaps in it and that is mainly because the lack of knowledge among the employees and they have never been informed of how to manage their passwords, computers and IT issues in general. Suggestions for improvement have been given and some implementations have been performed to eliminate the deficiencies.

  • 2.
    Ahmed, Tanvir Saif
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Markovic, Bratislav
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Distribuerade datalagringssystem för tjänsteleverantörer: Undersökning av olika användningsfall för distribuerade datalagringssystem2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this thesis, a study of three different uses cases has been made within the field of data storage, which are as following: Cold Storage, High Performance Storage and Virtual Machine Storage. The purpose of the survey is to give an overview of commercial distributed file systems and a deeper study of open source codes distributed file systems in order to find the most optimal solution for these use cases. Within the study, previous works concerning performance, data protection and costs were an-alyzed and compared in means to find different functionalities (snapshotting, multi-tenancy, data duplication and data replication) which distinguish modern distributed file systems. Both commercial and open distributed file systems were examined. A cost estimation for commercial and open distrib-uted file systems were made in means to find out the profitability for these two types of distributed file systems.After comparing and analyzing previous works, it was clear that the open source distributed file sys-tem Ceph was proper as a solution in accordance to the objectives that were set for High Performance Storage and Virtual Machine Storage. The cost estimation showed that it was more profitable to im-plement an open distributed file system. This study can be used as guidance to choose between different distributed file systems.

  • 3. Alesii, Roberto
    et al.
    Congiu, Roberto
    Santucci, Fortunato
    Di Marco, Piergiuseppe
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Architectures and protocols for fast identification in large-scale RFID systems2014In: ISCCSP 2014 - 2014 6th International Symposium on Communications, Control and Signal Processing, Proceedings, 2014, p. 243-246Conference paper (Refereed)
    Abstract [en]

    Passive tags based on backscattered signals yield low energy consumption for large-scale applications of RFIDs. In this paper, system architectures and protocol enhancements for fast identifications in ISO/IEC 18000-6C systems that integrate UWB technology are investigated. The anti-collision protocol is studied by considering various tag populations. A novel algorithm is proposed to adapt the UHF air interface parameters with the use of UWB ranging information. The results show that the proposed algorithm yields up to 25% potential performance improvement compared to the ISO/IEC 18000-6C standard.

  • 4.
    Altayr, Hydar
    et al.
    KTH, Superseded Departments, Computer and Systems Sciences, DSV.
    Adis, Michael
    KTH, Superseded Departments, Computer and Systems Sciences, DSV.
    Utveckling och design av WiGID2003Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The Center for Genomics and Bioinformatics (CGB) is an academic department at Karolinska Institute. Generally stated, the CGB department is committed to the generation and management of genetic information by approaches aiming at elucidating the connection between genes, protein and function.

    WiGID is a genome information database that is available through WAP (Wireless Application Protocol).

    Our version of WiGID is based on WML, PHP and PostgreSQL as a database server.

    One of the changes on the old WiGID application was the creation of a relational database with seven tables and one view, instead of the file that represented the database on the old version. We also changed the script language from python to PHP.

    The search engine ability has been extended with three new search alternatives for a user to choose from. Each choice leads to other, sometimes multiple choices.

    A GUI has been created for the administrator, to be able to insert information into the database.

    The structure of the search engine is primarily for narrowing down the search result on the phone display, thereby making the search efficient.

  • 5.
    Andersson, Andreas
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Spirometri med en smarttelefon: Utveckling av en app för att mäta rotationshastigheten till en spirometerprototyp för smarttelefoner2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The goal with this bachelor thesis was to develop an application with an algorithm to measure the rotation speed of a prototype, as a low-cost solution for measuring spirometry with a smartphone. In a pilot study it was investigated how a smartphone can be used to measure health and what algorithms there are to detect motion in videos. After the pilot study an app with the function to record a video by using the camera of a smartphone and then use an algorithm to detect the rotation speed in the spirometry-prototype’s turbine was developed. To make it work it is important that the rotation speed is low enough so it does not exceed half of the cameras fps. Therefore, to capture the rotation speed of the spirometry-prototype’s turbine the rotation needs to be limited and a smartphone with a camera with at least 120 fps is required.The result of this work is an algorithm that can measure the rotation speed in the spirometry prototype turbine. The algorithm is detecting the peaks in a PPG. To minimize the computation time and to increase the accuracy the algorithm analyses the colour intensity over a ROI in every frame. There is great potential to use this algorithm to further develop this alternative method of measuring spirometry.

  • 6.
    Araujo, Jose
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Sandberg, Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Experimental Validation of a Localization System Based on a Heterogeneous Sensor Network2009In: ASCC: 2009 7TH ASIAN CONTROL CONFERENCE, NEW YORK: IEEE , 2009, p. 465-470Conference paper (Refereed)
    Abstract [en]

    The experimental implementation and validation of a localization system based on a heterogeneous sensor network is described. The sensor network consists of ultrasound ranging sensors and web cameras. They are used to localize a mobile robot under sensor communication constraints. Applying a recently proposed sensor fusion algorithm that explicitly takes communication delay and cost into account, it is shown that one can accurately trade off the estimation performance by using low-quality ultrasound sensors with low processing time and low communication cost versus the use of the high-quality cameras with longer processing time and higher communication cost. It is shown that a periodic schedule of the sensors is suitable in many cases. The experimental setup is discussed in detail and experimental results are presented.

  • 7.
    Araya, Cristian
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Singh, Manjinder
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Web API protocol and security analysis2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    There is problem that every company has its own customer portal. This problem can be solved by creating a platform that gathers all customers’ portals in one place. For such platform, it is required a web API protocol that is fast, secure and has capacity for many users. Consequently, a survey of various web API protocols has been made by testing their performance and security.

    The task was to find out which web API protocol offered high security as well as high performance in terms of response time both at low and high load. This included an investigation of previous work to find out if certain protocols could be ruled out. During the work, the platform’s backend was also developed, which needed to implement chosen web API protocols that would later be tested. The performed tests measured the APIs’ connection time and their response time with and without load. The results were analyzed and showed that the protocols had both pros and cons. Finally, a protocol was chosen that was suitable for the platform because it offered high security and fast connection. In addition, the server was not affected negatively by the number of connections. Reactive REST was the web API protocol chosen for this platform.

  • 8.
    Arrospide Echegaray, Daniel
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Utvärdering av Självstyrandes-utvecklarramverket2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Within software engineering there is a diversity of process methods where each one has its specific purpose. A process method can be described as being a repeatable set of step with the purpose to achieve a task and reach a specific result. The majority of process methods found in this study are focused on the software product being developed. There seems to be a lack of process methods that can be used by software developers for there individual soft- ware process improvement. Individual software process improvement, refers to how the in- dividual software developer chooses to structure their own work with the purpose to obtain a specific result

    The Self-Governance Developer Framework (also called SGD-framework) whilst writing this is a newly developed process framework with the purpose of aiding the individual soft- ware developer to improve his own individual software process. Briefly explained the framework is intended to contain all the activities that can come up in a software project. The problem is that this tool has not yet been evaluated and therefore it is unknown if it is relevant for its purpose. To frame and guide the study three problem questions has been for- mulated (1) Is the framework complete for a smaller company in regards to it activities? (2) How high is the cost for the SGD-framework in regard of time?

    The goal of the study is to contribute for future studies for the framework by performing an action study where the Self-Governance Developer Framework is evaluated against a set of chosen evaluation criteria.

    An inductive qualitative research method was used when conducting the study. An induc- tive method means that conclusions are derived from empirically gathered data and from that data form general theories. Specifically, the action study method was used. Data was gathered by keeping a logbook and also time logging during the action study. To evaluate the framework, some evaluation criteria was used which were (1) Completeness, (2) Se- mantic correctness, (3) Cost. A narrative analysis was conducted over the data that was gathered for the criteria. The analysis took the problem formulations in regard.

    The results from the evaluation showed that the framework was not complete with the re- gards of the activities. Although next to complete as only a few activities were further needed during the action study. A total of 3 extra activities were added over the regular 40 activities. Around 10% of the time spent in activities were in activities outside of the Self- Governance Developer Framework. The activities were considered to finely comminute for the context of a smaller company. The framework was considered highly relevant for im- proving the individual software developers own process. The introduction cost in this study reflect on the time it took until the usage of the framework was considered consistent. In this study it was approximately 24 working days with a usage about 3.54% of an eight-hour work day. The total application cost of usage of the framework in the performed action study was on average 4.143 SEK/hour or 662,88 SEK/month. The template cost used was on 172.625 SEK/hour. 

  • 9.
    Aslamy, Benjamin
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Utveckling av ett multisensorsystem för falldetekteringsanordningar2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Accidental falls among the elderly is a major public health problem. As a result, a variety of systems have been developed for remote monitoring of the elderly to permit early detection of falls. The majority of the research that has been done so far in fall accidents has focused on developing new more successful algorithms spe- cifically to identify fall from non-fall. Although the statistics show that mortality and injuries caused by falls are increasing every year in conjunction with the in- creasing proportion of older people in the population.

    This thesis is about improving the current fall detection devices by covering the gaps and meet the needs of the current fall detection techniques. The improve- ments that have been identified is to provide a secure assessment of the patient's health and be able to call for aid more quickly when a fall occurs. Another im- provement is the mobility for the elderly to be outdoors and have the ability to per- form daily activities without being limited by the location position.

    In summary it can be said that a multisensor system in form of a prototype has been designed to cover the deficiencies and improvements that have been identi- fied. Apart from detection of falls and body movements through an accelerometer sensor the prototype does also include a sensor for detecting vital signs in form of ECG. It also supports cellular and wireless network communication in form of GPRS and Wi-Fi to enable freedom of movement for the elderly. Furthermore, the prototype includes a sensor for GPS that provides information about location position. 

  • 10.
    Aurell, Erik
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    El-Ansary, Sameh
    KTH, School of Engineering Sciences (SCI), Physics.
    A physics-style approach to scalability of distributed systems2005In: Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349, Vol. 3267, p. 266-272Article in journal (Refereed)
    Abstract [en]

    Is it possible to treat large scale distributed systems as physical systems? The importance of that question stems from the fact that the behavior of many P2P systems is very complex to analyze analytically, and simulation of scales of interest can be prohibitive. In Physics, however, one is accustomed to reasoning about large systems. The limit of very large systems may actually simplify the analysis. As a first example, we here analyze the effect of the density of populated nodes in an identifier space in a P2P system. We show that while the average path length is approximately given by a function of the number of populated nodes, there is a systematic effect which depends on the density. In other words, the dependence is both on the number of address nodes and the number of populated nodes, but only through their ratio. Interestingly, this effect is negative for finite densities, showing that an amount of randomness somewhat shortens average path length.

  • 11.
    Axtelius, Mathias
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Alsawadi, Rami
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    An improved selection algorithm for access points in wireless local area networks: An improved selection algorithm for wireless iopsys devices2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Wireless devices search for access points when they want to connect to a network. A devicechooses an access point based on the received signal strength between the device and theaccess point. That method is good for staying connected in a local area network but it doesnot always offer the best performance, which can result in a slower connection. This is thestandard method of connection for wireless clients, which will be referred to as the standardprotocol. Larger networks commonly have a lot of access points in an area, which increasesthe coverage area and makes loss of signal a rare occurrence. Overlapping coverage zonesare also common, offering multiple choices for a client. The company Inteno wanted an alternativeconnection method for their gateways. The new method that was developed wouldforce the client to connect to an access point depending on the bitrate to the master, as wellas the received signal strength. These factors are affected by many different parameters.These parameters were noise, signal strength, link-rate, bandwidth usage and connectiontype. A new metric had to be introduced to make the decision process easier by unifying theavailable parameters. The new metric that was introduced is called score. A score system wascreated based on these metrics. The best suited access point would be the one with the highestscore. The developed protocol chose the gateway with the highest bitrate available, while thestandard protocol would invariably pick the closest gateway regardless. The developed protocolcould have been integrated to the standard protocol to gain the benefits of both. Thiscould not be accomplished since the information was not easily accessible on Inteno’s gatewaysand had to be neglected in this thesis.

  • 12. Ben Dhaou, I.
    et al.
    Tenhunen, Hannu
    KTH, Superseded Departments, Electronic Systems Design.
    Efficient library characterization for high-level power estimation2004In: IEEE Transactions on Very Large Scale Integration (vlsi) Systems, ISSN 1063-8210, E-ISSN 1557-9999, Vol. 12, no 6, p. 657-661Article in journal (Refereed)
    Abstract [en]

    This paper describes LP-DSM, which is an algorithm used for efficient library characterization in high-level power estimation. LP-DSM characterizes the power consumption of building blocks using the entropy of primary inputs and primary outputs. The experimental results showed that over a wide range of benchmark circuits implemented using full custom design in 0.35-mum 3.3 V CMOS process the statistical performance (mean and maximum error) of LP-DSM is comparable or sometimes better than most of the published algorithms. Moreover, it was found that LP-DSM has the lowest prediction sum of squares, which makes it an efficient tool for power prediction. Furthermore, the complexity of the LP-DSM is linear in relation to the number of primary inputs (O(NI)), whereas state of the art published library characterization algorithms have a complexity of O(NI2).

  • 13.
    Bhatti, Muhammad Khurram
    et al.
    Informat Technol Univ, Embedded Comp Lab, 346-B Ferozpur Rd, Lahore, Pakistan..
    Oz, Isil
    Izmir Inst Technol, Comp Engn Dept, Izmir, Turkey..
    Amin, Sarah
    Informat Technol Univ, Embedded Comp Lab, 346-B Ferozpur Rd, Lahore, Pakistan..
    Mushtaq, Maria
    Informat Technol Univ, Embedded Comp Lab, 346-B Ferozpur Rd, Lahore, Pakistan..
    Farooq, Umer
    Dhofar Univ, Dept Elect & Comp Engn, Salalah 211, Oman..
    Popov, Sergei
    SICS, Isafjordsgatan 22, S-16429 Kista, Sweden..
    Brorsson, Mats
    KTH, School of Electrical Engineering and Computer Science (EECS), Software and Computer systems, SCS.
    Locality-aware task scheduling for homogeneous parallel computing systems2018In: Computing, ISSN 0010-485X, E-ISSN 1436-5057, Vol. 100, no 6, p. 557-595Article in journal (Refereed)
    Abstract [en]

    In systems with complex many-core cache hierarchy, exploiting data locality can significantly reduce execution time and energy consumption of parallel applications. Locality can be exploited at various hardware and software layers. For instance, by implementing private and shared caches in a multi-level fashion, recent hardware designs are already optimised for locality. However, this would all be useless if the software scheduling does not cast the execution in a manner that promotes locality available in the programs themselves. Since programs for parallel systems consist of tasks executed simultaneously, task scheduling becomes crucial for the performance in multi-level cache architectures. This paper presents a heuristic algorithm for homogeneous multi-core systems called locality-aware task scheduling (LeTS). The LeTS heuristic is a work-conserving algorithm that takes into account both locality and load balancing in order to reduce the execution time of target applications. The working principle of LeTS is based on two distinctive phases, namely; working task group formation phase (WTG-FP) and working task group ordering phase (WTG-OP). The WTG-FP forms groups of tasks in order to capture data reuse across tasks while the WTG-OP determines an optimal order of execution for task groups that minimizes the reuse distance of shared data between tasks. We have performed experiments using randomly generated task graphs by varying three major performance parameters, namely: (1) communication to computation ratio (CCR) between 0.1 and 1.0, (2) application size, i.e., task graphs comprising of 50-, 100-, and 300-tasks per graph, and (3) number of cores with 2-, 4-, 8-, and 16-cores execution scenarios. We have also performed experiments using selected real-world applications. The LeTS heuristic reduces overall execution time of applications by exploiting inter-task data locality. Results show that LeTS outperforms state-of-the-art algorithms in amortizing inter-task communication cost.

  • 14.
    Bhuddi, Amita
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Somos, Oliver
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Återställningsverktyg för fordon baserat på applikationsintegration2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The software testing team at Scania use a manual and time consuming process to restore a test vehicle after working with it. Several different applications are used in this process to ensure the vehicle is in the same state as it was before their testing. To improve the workflow with a reduced workload and a more robust process, the test team was interested in the development of a restoration application. It was desired to develop the restoration application by reusing the components to the greatest possible extend. Since there were many components that fulfilled the needs of most functions, a pre-study of all the applications was done to decide which components can be re-used. This was study was based on the integration model, Enterprise Application Integration, which aims to create a single product combining the applications used in an organization to simplify processes such as maintenance, data management and employee training. A prototype was developed which implements three existing modules on different levels and, in line with the goals of EAI, is itself a simple application that enables the components to work in unision

  • 15.
    Bilardi, Gianfranco
    et al.
    Univ Padua, Dept Informat Engn, I-35131 Padua, Italy..
    Scquizzato, Michele
    KTH, School of Electrical Engineering and Computer Science (EECS), Theoretical Computer Science, TCS. Univ Padua, Padua, Italy.
    Silvestri, Francesco
    Univ Padua, Dept Informat Engn, I-35131 Padua, Italy..
    A Lower Bound Technique for Communication in BSP2018In: ACM TRANSACTIONS ON PARALLEL COMPUTING, ISSN 2329-4949, Vol. 4, no 3, article id UNSP 14Article in journal (Refereed)
    Abstract [en]

    Communication is a major factor determining the performance of algorithms on current computing systems; it is therefore valuable to provide tight lower bounds on the communication complexity of computations. This article presents a lower bound technique for the communication complexity in the bulk-synchronous parallel (BSP) model of a given class of DAG computations. The derived bound is expressed in terms of the switching potential of a DAG, that is, the number of permutations that the DAG can realize when viewed as a switching network. The proposed technique yields tight lower bounds for the fast Fourier transform (FFT), and for any sorting and permutation network. A stronger bound is also derived for the periodic balanced sorting network, by applying this technique to suitable subnetworks. Finally, we demonstrate that the switching potential captures communication requirements even in computational models different from BSP, such as the I/O model and the LPRAM.

  • 16.
    Blanco Paananen, Adrian
    et al.
    KTH, School of Computer Science and Communication (CSC).
    Storby, Johan
    KTH, School of Computer Science and Communication (CSC).
    Observing coevolution in simulated bacteria: Using asexual reproduction and simple direct mapped functions for decision-making2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this report we have presented the results of a program which performs simula- tions of artificial bacteria with the ability to evolve different characteristics and behaviours through genetic algorithms. Over time unfit bacteria will die out, and the more fit bacteria will produce offspring with slightly mutated variants of it’s genetic code resembling the evolutionary process. The simulation does not follow the traditional macro-scale hand-picked sexual reproduction often used in genetic algorithms to produce optimal results, but it instead uses individ- ual asexual reproduction which more closely resembles how bacteria reproduce in nature. Furthermore we do not use traditional neural networks for decision making, but simple functions which directly map the bacterias inputs to their decisions.

    The purpose of this study was to observe whether bacteria with different initial starting populations would coevolve, and specialize into heterogeneous populations. Furthermore we have tried to analyze how the populations inter- act with each other and how changing the different parameters of the simulation would affect the populations. We have performed three separate experiments that differ in their initial conditions, one with pre-created and heterogeneous herbivores and carnivores, one with homogeneous omnivores, and one with bac- teria whose genetic values have been decided at random. The result of our experiments was that we observed coevolution in the bacteria, and that they would despite very different initial starting conditions always grow towards sta- ble heterogeneous populations with very few exceptions. 

  • 17.
    Blom, Marcus
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Hammar, Kim
    KTH, School of Information and Communication Technology (ICT).
    Integrating Monitoring Systems - Pre-Study2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Failures in networks that reside in business environments cause harm to organizations depending on them. Every minute of inoperativety is hurtful and as a network adminstrator you want to minimize the rates of failures as well as the time of inoperation. Therefore, a fruitful network monitoring system is of great interest for such organizations. This bachelor’s thesis is the outcome of a pre-study performed on behalf of MIC Nordic and sought to advice them in the implementation of a new monitoring system.

    The aim of this study was to investigate how a Network Operation Center (NOC) can be implemented in an existing monitoring environment, to integrate current monitoring systems to a central point for monitoring. This study takes an holitstic approach to network management and the research can be divided into two main categories: Communication between network components and Presentation of information. Our process involves an analysis of the environment of MIC Nordic and an in depth inquiry on the current state of network monitoring and interface design. The study then culminates in the implementation of a prototype. The prototype serves in first hand as a research tool to collect experience and empirical evidence to increase the crediblity of our conclusions. It is also an attempt of demonstrating the complete process behind developing a NOC, that we believe can fill a gap among the previous research in the field.

    From our results you can expect a prototype with functionality for monitoring network components and a graphical user interface (GUI) for displaying information. The results are designed towards solving the specific network management problem that was given and the environment that it concerns. This pre-study suggests that the best solution for implementing a NOC in the given environment is to use SNMP for communication. From an investigation on how to present network management information in a effective way we propose to follow a user-centered approach and to utilize human perception theory in the design process. The authors recommend further research that maintain the holistic approach but applies more quantitative methods to broaden the scope.

  • 18. Bonnichsen, L.
    et al.
    Podobas, Artur
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Using transactional memory to avoid blocking in OpenMP synchronization directives: Don’t wait, speculate!2015In: 11th International Workshop on OpenMP, IWOMP 2015, Springer, 2015, p. 149-161Conference paper (Refereed)
    Abstract [en]

    OpenMP applications with abundant parallelism are often characterized by their high-performance. Unfortunately, OpenMP applications with a lot of synchronization or serialization-points perform poorly because of blocking, i.e. the threads have to wait for each other. In this paper, we present methods based on hardware transactional memory (HTM) for executing OpenMP barrier, critical, and taskwait directives without blocking. Although HTM is still relatively new in the Intel and IBM architectures, we experimentally show a 73% performance improvement over traditional locking approaches, and 23% better than other HTM approaches on critical sections. Speculation over barriers can decrease execution time by up-to 41 %. We expect that future systems with HTM support and more cores will have a greater benefit from our approach as they are more likely to block.

  • 19.
    Braun, Stefan
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Wafer-level heterogeneous integration of MEMS actuators2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents methods for the wafer-level integration of shape memory alloy (SMA) and electrostatic actuators to functionalize MEMS devices. The integration methods are based on heterogeneous integration, which is the integration of different materials and technologies. Background information about the actuators and the integration method is provided.

    SMA microactuators offer the highest work density of all MEMS actuators, however, they are not yet a standard MEMS material, partially due to the lack of proper wafer-level integration methods. This thesis presents methods for the wafer-level heterogeneous integration of bulk SMA sheets and wires with silicon microstructures. First concepts and experiments are presented for integrating SMA actuators with knife gate microvalves, which are introduced in this thesis. These microvalves feature a gate moving out-of-plane to regulate a gas flow and first measurements indicate outstanding pneumatic performance in relation to the consumed silicon footprint area. This part of the work also includes a novel technique for the footprint and thickness independent selective release of Au-Si eutectically bonded microstructures based on localized electrochemical etching.

    Electrostatic actuators are presented to functionalize MEMS crossbar switches, which are intended for the automated reconfiguration of copper-wire telecommunication networks and must allow to interconnect a number of input lines to a number of output lines in any combination desired. Following the concepts of heterogeneous integration, the device is divided into two parts which are fabricated separately and then assembled. One part contains an array of double-pole single-throw S-shaped actuator MEMS switches. The other part contains a signal line routing network which is interconnected by the switches after assembly of the two parts. The assembly is based on patterned adhesive wafer bonding and results in wafer-level encapsulation of the switch array. During operation, the switches in these arrays must be individually addressable. Instead of controlling each element with individual control lines, this thesis investigates a row/column addressing scheme to individually pull in or pull out single electrostatic actuators in the array with maximum operational reliability, determined by the statistical parameters of the pull-in and pull-out characteristics of the actuators.

  • 20.
    Brejcha, Kevin
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Prestandaanalys av HTTP/22015Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Swedbank is one of Sweden’s biggest banks with estimated four million private customers and they are constantly trying to improve their services so they become more user-friendly and faster. To satisfy their customer’s need of fast and easy services Swedbank wants to lower the loading times on the web services to the user experience is faster and smoother, especially for the users doing their banking on a smartphone. The mission is to do a per-formance analysis of the new HTTP protocol HTTP/2 and take out the most essential parts so Swedbank knows what to take advantage of when installing the new versions on their servers to achieve optimal services.The results showed that after implementing HTTP/2’s new features, Swedbank’s website performance increased with 44% in total loading time. The tests were performed in a local experimental environment where the earlier HTTP versions was installed and the perfor-mance metrics was documented.

  • 21.
    Brink, Pontus
    et al.
    KTH, School of Computer Science and Communication (CSC).
    Rinnarv, Jonathan
    KTH, School of Computer Science and Communication (CSC).
    Machine learning - neuroevolution for designing chip circuits/pathfinding2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Neural Networks have been applied in numeral broad categories of work. Such as classification, data processing, robotics, systemcontrol e.t.c. This thesis compares using traditional methods of the routing process in chip circuit design to using a Neural Network trained with evolution. Constructing and evaluating a chip design is a complicated thing, where a lot of variables have to be accounted for and therefore a simplified evaluation and design process is used in order to train the network and compare the results. This was done by constructing simple test cases and running the algorithms BFS, A*Star and the neural network and comparing the paths each algorithm found using a fitness function. The results were that BFS and A*Star both performed better on complex circuits, but the neural network was able to create better paths on very small and niche circuits. The conclusion of the study is that the neural network approach is not able to compete with the standard industry methods of the routing process, but we do not exclude the possibility that with a better designed Fitness function, this could be possible.

  • 22.
    Brorsson, Mats
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Software and Computer Systems, SCS.
    Collin, Mikael
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Software and Computer Systems, SCS.
    Adaptive and flexible dictionary code compression for embedded applications2006In: Proceedings of the 2006 international conference on Compilers, architecture and synthesis for embedded systems, 2006, p. 113-124Conference paper (Refereed)
    Abstract [en]

    Dictionary code compression is a technique where long instructions in the memory are replaced with shorter code words used as index in a table to look up the original instructions. We present a new view of dictionary code compression for moderately high-performance processors for embedded applications. Previous work with dictionary code compression has shown decent performance and energy savings results which we verify with our own measurement that are more thorough than previously published. We also augment previous work with a more thorough analysis on the effects of cache and line size changes. In addition, we introduce the concept of aggregated profiling to allow for two or more programs to share the same dictionary contents. Finally, we also introduce dynamic dictionaries where the dictionary contents is considered to be part of the context of a process and show that the performance overhead of reloading the dictionary contents on a context switch is negligible while on the same time we can save considerable energy with a more specialized dictionary contents.

  • 23.
    Bruse, Andreas
    KTH, School of Computer Science and Communication (CSC).
    Exploiting Cloud Resources For Semantic Scene Understanding On Mobile Robots2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Modern day mobile robots are constrained in the resources available to them. Only so much hardware can be fit onto the robotic frame and at the same time they are required to perform tasks that require lots of computational resources, access to massive amounts of data and the ability to share knowledge with other robots around it.

    This thesis explores the cloud robotics approach in which complex compu- tations can be offloaded to a cloud service which can have a huge amount of computational resources and access to massive data sets. The Robot Operat- ing System, ROS, is extended to allow the robot to communicate with a high powered cluster and this system is used to test our approach on such a complex task as semantic scene understanding. The benefits of the cloud approach is utilized to connect to a cloud based object detection system and to build a cat- egorization system relying on large scale datasets and a parallel computation model. Finally a method is proposed for building a consistent scene description by exploiting semantic relationships between objects.

  • 24.
    Burghout, Wilco
    KTH, Superseded Departments, Infrastructure.
    Hybrid microscopic-mesoscopic traffic simulation2004Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    Traffic simulation is an important tool for modelling the operations of dynamic traffic systems and helps analyse the causes and potential solutions of traffic problems such as congestion and traffic safety. Microscopic simulation models provide a detailed representation of the traffic process, which makes them most suitable for evaluation of complicated traffic facilities and Intelligent Transportation Systems that often consist of complex traffic management, safety and information systems. Macroscopic and mesoscopic models on the other hand, capture traffic dynamics in lesser detail, but are faster and easier to apply and calibrate than microscopic models. Therefore they are most suitable for modelling large networks, while microscopic models are usually applied to smaller areas.

    The objective of this thesis is to combine the strengths of both modelling approaches and diminish their individual weaknesses by constructing a hybrid mesoscopic-microscopic model that applies microscopic simulation to areas of specific interest, while simulating a surrounding network in lesser detail with a mesoscopic model.

    Earlier attempts at hybrid modelling have concentrated on integrating macroscopic and microscopic models and have proved difficult due to the large difference between the continuous-flow representation of traffic in macroscopic models and the detailed vehicle-and driver-behaviour represented in microscopic models. These problems are solved in this thesis by developing a mesoscopic vehicle-based and event-based model that avoids the (dis)aggregation problems of traffic flows at the inter-model boundaries. In addition, this thesis focuses on the general problems of consistency across the entire hybrid model.

    The requirements are identified that are important for a hybrid model to be consistent across the models at different levels of detail. These requirements vary from network and route-choice consistency to consistency of traffic dynamics across the boundaries of the micro- and mesoscopic submodels. An integration framework is proposed that satisfies these requirements. This integration framework has been implemented in a prototype hybrid model, MiMe, which is used to demonstrate the correctness of the solutions to the various integration issues. The hybrid model integrates MITSIMLab, a microscopic traffic simulation model, and Mezzo, the newly developed mesoscopic model. Both the hybrid model and the new Mezzo model are applied in a number of case studies, including a network in the North of Stockholm, which show their validity and applicability. The results are promising and support both the proposed integration architecture and the importance of integrating microscopic and mesoscopic models.

  • 25. Calandriello, Giorgio
    et al.
    Papadimitratos, Panos
    Hubaux, Jean-Pierre
    Lioy, Antonio
    Efficient and Robust Pseudonymous Authentication in VANET2007In: VANET'07: PROCEEDINGS OF THE FOURTH ACM INTERNATIONAL WORKSHOP ON VEHICULAR AD HOC NETWORKS, 2007, p. 19-27Conference paper (Refereed)
    Abstract [en]

    Effective and robust operations, as well as security and privacy are critical for the deployment of vehicular ad hoc networks (VANETs). Efficient and easy-to-manage security and privacy-enhancing mechanisms axe essential for the wide-spread adoption of the VANET technology. In this paper, we are concerned with this problem; and in particular, how to achieve efficient and robust pseudonym-based authentication. We design mechanisms that reduce the security overhead for safety beaconing, and retain robustness for transportation safety, even in adverse network settings. Moreover, we show how to enhance the availability and usability of privacy-enhancing VANET mechanisms: Our proposal enables vehicle on-board units to generate their own pseudonyms, without affecting the system security.

  • 26.
    Carlzon, Malin
    KTH, School of Computer Science and Communication (CSC), Numerical Analysis and Computer Science, NADA.
    BGP oscillations when peering with loopback addresses2006In: 20th International Conference on Advanced Information Networking and Applications, Vol 2, Proceedings / [ed] Martin DC, LOS ALAMITOS, USA: IEEE COMPUTER SOC , 2006, p. 712-716Conference paper (Refereed)
    Abstract [en]

    An oscillating routing protocol will result in increased protocol activity and may lead to increased router CPU activity and memory consumption.  This case study shows that BGP peering using loopback addresses when peering EBGP between two dualhomed ASes will cause BGP to oscillate. It includes a detailed lab report in which several possible setups that will cause BGP to oscillate are presented. It also includes an oscillation event from one of the world's largest production networks that was caused by such a setup.

  • 27.
    Carlzon, Malin
    KTH, School of Computer Science and Communication (CSC), Numerical Analysis and Computer Science, NADA.
    Improving BGP convergence properties and web content blocking using BGP2006Licentiate thesis, comprehensive summary (Other scientific)
  • 28.
    Carlzon, Malin
    KTH, School of Computer Science and Communication (CSC), Numerical Analysis and Computer Science, NADA.
    Perceived problems with BGP: a survey2006Report (Other academic)
  • 29.
    Carlzon, Malin
    KTH, School of Computer Science and Communication (CSC), Numerical Analysis and Computer Science, NADA.
    Resetting a damped out route in BGP2006Report (Other academic)
  • 30.
    Carlzon, Malin
    et al.
    KTH, School of Computer Science and Communication (CSC), Numerical Analysis and Computer Science, NADA.
    Hagsand, Olof
    KTH, School of Computer Science and Communication (CSC), Numerical Analysis and Computer Science, NADA.
    Widell, Fredrik
    KTH, School of Computer Science and Communication (CSC), Numerical Analysis and Computer Science, NADA.
    Danielsson, Björn
    KTH, School of Computer Science and Communication (CSC), Numerical Analysis and Computer Science, NADA.
    Blocking web contents using BGP: measurements and observations2006Report (Other academic)
  • 31. Casoni, E.
    et al.
    Jerusalem, A.
    Samaniego, C.
    Eguzkitza, B.
    Lafortune, P.
    Tjahjanto, Denny
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.). IMDEA Materials Institute, Spain .
    Saez, X.
    Houzeaux, G.
    Vazquez, M.
    Alya: Computational Solid Mechanics for Supercomputers2015In: Archives of Computational Methods in Engineering, ISSN 1134-3060, E-ISSN 1886-1784, Vol. 22, no 4, p. 557-576Article, review/survey (Refereed)
    Abstract [en]

    While solid mechanics codes are now conventional tools both in industry and research, the increasingly more exigent requirements of both sectors are fuelling the need for more computational power and more advanced algorithms. For obvious reasons, commercial codes are lagging behind academic codes often dedicated either to the implementation of one new technique, or the upscaling of current conventional codes to tackle massively large scale computational problems. Only in a few cases, both approaches have been followed simultaneously. In this article, a solid mechanics simulation strategy for parallel supercomputers based on a hybrid approach is presented. Hybrid parallelization exploits the thread-level parallelism of multicore architectures, combining MPI tasks with OpenMP threads. This paper describes the proposed strategy, programmed in Alya, a parallel multi-physics code. Hybrid parallelization is specially well suited for the current trend of supercomputers, namely large clusters of multicores. The strategy is assessed through transient non-linear solid mechanics problems, both for explicit and implicit schemes, running on thousands of cores. In order to demonstrate the flexibility of the proposed strategy under advance algorithmic evolution of computational mechanics, a non-local parallel overset meshes method (Chimera-like) is implemented and the conservation of the scalability is demonstrated.

  • 32.
    Chabloz, Jean-Michel
    et al.
    KTH, School of Information and Communication Technology (ICT), Electronic Systems.
    Hemani, Ahmed
    KTH, School of Information and Communication Technology (ICT), Electronic Systems.
    Lowering the Latency of Interfaces for Rationally-Related Frequencies2010In: 2010 IEEE INTERNATIONAL CONFERENCE ON COMPUTER DESIGN, 2010, p. 23-30Conference paper (Refereed)
    Abstract [en]

    We have introduced the Globally-Ratiochronous, Locally-Synchronous (GRLS) design paradigm, a design style based on rationally-related frequencies, with the objective to overcome the limitations of traditional multi-frequency systems by providing a flexibility close that of Globally-Asynchronous, Locally-Synchronous (GALS) systems but introducing performance penalties and overheads close to those of mesochronous systems. In this paper we focus on performances and improve the latency figures of our original GRLS interfaces by introducing two new interfaces, called GRLS-F and GRLS-noF, the first suitable for blocks with long computation time and the second for blocks with short computation time. The latency figures of the original GRLS interfaces are improved up to 50% without increasing complexity. The average latency figures of the resulting interfaces are lower than 1 Receiver clock cycle, the latency of a synchronous interface.

  • 33.
    Chavez Alcarraz, Erick
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Moraga, Manuel
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Linked data performance in different databases: Comparison between SQL and NoSQL databases2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Meepo AB was investigating the possibility of developing a social rating and recommendation service. In a recommendation service, the user ratings are collected in a database, this data is then used in recommendation algorithms to create individual user recommendations.

    The purpose of this study was to find out which  demands are put on a DBMS, database management system, powering a recommendation service, what impact the NoSQL databases have on the performance of recommendation services compared to traditional relational databases, and which DBMS is most suited for storing the data needed to host a recommendation service.

    Five distinct NoSQL and Relational DBMS were examined, from these three candidates were chosen for a closer comparison.

    Following a study of recommendation algorithms and services, a test suite was created to compare DBMS performance in different areas using a data set of 100 million ratings.

    The results show that MongoDB had the best performance in most use cases, while Neo4j and MySQL struggled with queries spanning the whole data set.

    This paper however never compared performance for real production code. To get a better comparison, more research is needed. We recommend new performance tests for MongoDB and Neo4j using implementations of recommendation algorithms, a larger data set, and more powerful hardware.

  • 34.
    Chen, Xiaowen
    et al.
    KTH, School of Electrical Engineering (EES).
    Lu, Zhonghai
    KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK. KTH, School of Information and Communication Technology (ICT), Electronics.
    Liu, S.
    Chen, S.
    Round-trip DRAM access fairness in 3D NoC-based many-core systems2017In: ACM Transactions on Embedded Computing Systems, ISSN 1539-9087, E-ISSN 1558-3465, Vol. 16, no 5s, article id 162Article in journal (Refereed)
    Abstract [en]

    In 3D NoC-based many-core systems, DRAM accesses behave differently due to their different communication distances and the latency gap of different DRAM accesses becomes bigger as the network size increases, which leads to unfair DRAM access performance among different nodes. This phenomenon may lead to high latencies for some DRAM accesses that become the performance bottleneck of the system. The paper addresses the DRAM access fairness problem in 3D NoC-based many-core systems by narrowing the latency difference of DRAM accesses as well as reducing the maximum latency. Firstly, the latency of a round-trip DRAM access is modeled and the factors causing DRAM access latency difference are discussed in detail. Secondly, the DRAM access fairness is further quantitatively analyzed through experiments. Thirdly, we propose to predict the network latency of round-trip DRAM accesses and use the predicted round-trip DRAM access time as the basis to prioritize the DRAM accesses in DRAM interfaces so that the DRAM accesses with potential high latencies can be transferred as early and fast as possible, thus achieving fair DRAM access. Experiments with synthetic and application workloads validate that our approach can achieve fair DRAM access and outperform the traditional First-Come-First-Serve (FCFS) scheduling policy and the scheduling policies proposed by reference [7] and [24] in terms of maximum latency, Latency Standard Deviation (LSD)1 and speedup. In the experiments, the maximum improvement of the maximum latency, LSD, and speedup are 12.8%, 6.57%, and 8.3% respectively. Besides, our proposal brings very small extra hardware overhead (<0.6%) in comparison to the three counterparts.

  • 35.
    Chivi, Daniel
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Östling Gran, Joakim
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Administration av API-drivna enheter och tjänster för slutanvändare: En fallstudie av API-tjänster2018Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Nowadays people tend to use services and appliances that are managed seperately. This thesis examines the possibility of connecting different services into one main web application to faciliate communication between these services.

    A Great Thing have embraced the need of connecting applications to a single device and therefore, wants to create a web application integrated with the use of agents. These agents are built to manage the events a user request. For example ”Play a song at a specific time”.

    The methodology applied has partly been a case study and partly user-based methods in form of a survery and a user test. Further research was conducted on communication between service API:s and the necessary parameters that exchange data. Finally, the developed prototype was evaluated according to some usability guidelines.

    The thesis’s results are presented in the form of a web prototype focused on usability, implementation of APIs, user test of actual users and statistics of demanded services. In addition, a market research has been conducted to highlight economic benefits through API distribution. The conclusion is drawn that it is possible to link API:s and their services to achieve a user-friendly interface and how to use different parameters in an efficient way. Furthermore, the hope is that external readers will understand how the connection between API:s works in a structured and informative approach. Also how different technical methods for usability can be applied in construction of prototypes.

  • 36.
    Ciobanu Morogan, Matei
    KTH, School of Information and Communication Technology (ICT), Computer and Systems Sciences, DSV.
    Security system for ad-hoc wireless networks based on generic secure objects2005Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    As computing devices and wireless connectivity become ubiquitous, new usage scenarios emerge, where wireless communication links between mobile devices are established in an ad-hoc manner. The resulting wireless ad-hoc networks differ from classical computer networks in a number of ways, lack of permanent access to the global network and heterogeneous structure being some of them. Therefore, security services and mechanisms that have been designed for classical computer networks are not always the optimal solution in an ad-hoc network environment.

    The research is focused on analyzing how standard security services that are available in classical networks can be provided in an ad-hoc wireless network environment. The goal is to design a security system optimized for operation in ad-hoc wireless networks that provides the same security services – authentication, access control, data confidentiality and integrity, non-repudiation – currently available in classic wired networks.

    The first part of the thesis is the design and implementation of a security platform based on generic secure objects. The flexible and modular nature of this platform makes it suitable for deployment on devices that form ad-hoc networks – ranging from Java-enabled phones to PDAs and laptops.

    We then investigate the problems that appear when implementing in ad-hoc networks some of the security technologies that are standard building blocks of secure systems in classical computer networks. Two such technologies have been found to present problems, namely the areas of certification and access control. In a series of articles, we have described the problems that appear and devised solutions to them by designing protocols, techniques and extensions to standards that are optimized for usage in the ad-hoc network environment.

    These techniques, together with the functionality provided by the underlying security platform, are used to implement all standard security services – confidentiality, authentication, access control, non repudiation and integrity, allowing to integrate ad-hoc networks into the existing security infrastructure.

  • 37.
    Clemmedsson, Elin
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Marketing and Entrepreneurship.
    Identifying Pitfalls in Machine Learning Implementation Projects: A Case Study of Four Technology-Intensive Organizations2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis undertook the investigation of finding often occurring mistakes and problems that organizations face when conducting machine learning implementation projects. Machine learning is a technology with the strength of providing insights from large amounts of data. This business value generating technology has been defined to be in a stage of inflated expectations which potentially will cause organizations problems when doing implementation projects without previous knowledge. By a literature review and hypothesis formation followed by interviews with a sample group of companies, three conclusions are drawn from the results. First, indications show there is a correlation between an overestimation of the opportunities of machine learning and how much experience an organization has within the area. Second, it is concluded that data related pitfalls, such as not having enough data, low quality of the data, or biased data, are the most severe. Last, it is shown that realizing the value of long-term solutions regarding machine learning projects is difficult, although the ability increases with experience.

  • 38.
    Collin, Mikael
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Software and Computer Systems, SCS.
    Brorsson, Mats
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Software and Computer Systems, SCS.
    Öberg, Johnny
    KTH, School of Information and Communication Technology (ICT), Electronic Systems.
    A performance and energy exploration of dictionary code compression architectures2011In: 2011 International  Green Computing Conference and Workshops (IGCC), IEEE conference proceedings, 2011, p. 1-8Conference paper (Refereed)
    Abstract [en]

    We have made a performance and energy exploration of a previously proposed dictionary code compression mechanism where frequently executed individual instructions and/or sequences are replaced in memory with short code words. Our simulated design shows a dramatically reduced instruction memory access frequency leading to a performance improvement for small instruction cache sizes and to significantly reduced energy consumption in the instruction fetch path. We have evaluated the performance and energy implications of three architectural parameters: branch prediction accuracy, instruction cache size and organization. To asses the complexity of the design we have implemented the critical stages in VHDL.

  • 39. Cornwall, L. A.
    et al.
    Jensen, J.
    Kelsey, D. P.
    Frohner, Á.
    Kouřil, D.
    Bonnassieux, F.
    Nicoud, S.
    Lorentey, K.
    Hahkala, J.
    Silander, M.
    Cecchini, R.
    Ciaschini, V.
    dell'Agnello, L.
    Spataro, F.
    O'Callaghan, D.
    Mulmo, Olle
    KTH, Superseded Departments, Numerical Analysis and Computer Science, NADA.
    Volpato, Gian Luca
    KTH, Superseded Departments, Numerical Analysis and Computer Science, NADA.
    Groep, D.
    Steenbakkers, M.
    Mcnab, A.
    Authentication and authorization mechanisms for multi-domain grid environments2004In: Journal of Grid Computing, ISSN 1570-7873, E-ISSN 1572-9184, Vol. 2, no 4, p. 301-311Article in journal (Refereed)
    Abstract [en]

    This article discusses the authentication and the authorization aspects of security in grid environments spanning multiple administrative domains. Achievements in these areas are presented using the EU DataGrid project as an example implementation. It also gives an outlook on future directions of development.

  • 40. D'Angelo, M.
    et al.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    How to select the OOK detection threshold in wireless ad hoc and sensor networks2009In: IEEE Vehicular Technology Conference / [ed] 69th IEEE Vehicular Technology Conference Barcelona, SPAIN, APR 26-29, 2009, 2009Conference paper (Refereed)
    Abstract [en]

    On-off keying (OOK) is an attractive modulation technique to reduce energy consumption of power-constrained wireless networks. The OOK detection threshold, however, must be carefully selected to minimize the bit error probability (BER). This is a challenging task to accomplish on resource-limited nodes or on networks with high-mobility. In this paper, an efficient algorithm to compute the optimal threshold is proposed. The system scenario considers nodes simultaneously transmitting over same frequencies in Rayleigh-log-normal or Rice-log-normal fading conditions. It is shown that by using the Stirling expansion for the BER, and a log-normal approximation, a quick contraction-mapping can be built to achieve the threshold numerically. The mapping is simple to implement and converges quickly. Numerical simulations verify the validity of the theoretical analysis, and show that the new algorithm performs quite well in scenarios of practical interest.

  • 41. Darrell, T. J.
    et al.
    Yeh, T.
    Tollmar, Konrad
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Photo-based mobile deixis system and related techniques2004Patent (Other (popular science, discussion, etc.))
  • 42. Di Gregorio, S.
    et al.
    Umeton, R.
    Bicocchi, A.
    Evangelisti, A.
    Gonzalez, Meliza Contreras
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Highway traffic model based on cellular automata: Preliminary simulation results with congestion pricing considerations2008In: Eur. Model. Simul. Symp., EMSS, 2008, p. 665-674Conference paper (Refereed)
    Abstract [en]

    Cellular Automata are a reputable formal support for traffic modelling and simulation. STRATUNA is a Cellular Automata model for simulating the evolution of two/three lane highways. It encodes the wide specification of driver's response to the events in his sight range. Encouraging comparison between simulated events and their corresponding in the reality bring to the specification of a theoretical general model characterized by an increased expression power and a significantly deeper forecasting potential, whose application fields are numerous and varied. Fair results in flow forecasting lead to the implementation of an established cost system in which simulation directly provides cost forecasting in terms of congestion toll.

  • 43.
    Di Marco, Piergiuseppe
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Park, Pan Gun
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    A dynamic energy-efficient protocol for reliable and timely communications for wireless sensor networks in control and automation2009In: 2009 6th IEEE Annual Communications Society Conference on Sensor, Mesh and Ad Hoc Communications and Networks Workshops, 2009, Vol. SECON Workshops 2009, p. 146-148Conference paper (Refereed)
    Abstract [en]

    Designing quality of service (QoS) guaranteed communication protocol for wireless sensor networks (WSNs) is essential to exploit the advantages and flexibilities offered by this technology for real-time control and actuation applications. A novel cross-layer protocol that embraces altogether a semirandom routing, MAC, data aggregation, and radio power control for clustered WSNs is presented. The protocol leverages the combination of a randomized and a deterministic approach to ensure robustness over unreliable channels and packet losses. An optimization problem, whose objective function is the network energy consumption, and the constraints are reliability and latency of the packets is modelled and solved to adaptively select the protocol parameters by a simple algorithm. As a relevant contribution, the proposed protocol is completely implemented on a test-bed, and it is compared to existing protocols. Experimental results validate the analysis and show excellent performance in terms of reliability, latency, low node duty cycle, load balancing and dynamic adaptation to the application requirements.

  • 44.
    Di Marco, Piergiuseppe
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Park, Pan Gun
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    TREnD: A timely, reliable, energy-efficient and dynamic wsn protocol for control applications2010In: IEEE International Conference on Communications, 2010Conference paper (Refereed)
    Abstract [en]

    Control applications over wireless sensor networks (WSNs) require timely, reliable, and energy efficient communications. Cross-layer interaction is an essential design paradigm to exploit the complex interaction among the layers of the protocol stack and reach a maximum efficiency. Such a design approach is challenging because reliability and latency of delivered packets and energy are at odds, and resource constrained nodes support only simple algorithms. In this paper, the TREnD protocol is introduced for control applications over WSNs in industrial environments. It is a cross-layer protocol that embraces efficiently routing algorithm, MAC, data aggregation, duty cycling, and radio power control. The protocol parameters are adapted by an optimization problem, whose objective function is the network energy consumption, and the constraints are the reliability and latency of the packets. TREnD uses a simple algorithm that allows the network to meet the reliability and latency required by the control application while minimizing for energy consumption. TREnD is implemented on a test-bed and compared to some existing protocols. Experimental results show good performance in terms of reliability, latency, low duty cycle, and load balancing for both static and time-varying scenarios.

  • 45.
    Dilén, Erik
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Lundmark, Emil
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    En utvärdering av Windows 8 Store applikationer som plattform för VOD-tjänster2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    As an effect of Video On Demand (VOD)-usage growing fast June, as a software provider for the television industry, wants to acquire skills and evaluate Windows 8 applications as a platform for VOD services. June already delivers a web-based solution for VOD and now wants a comparison and evaluation of particular knowledge required, time, complexity, data caching, advantages and disadvantages of a Windows 8 application set against this web solution.

    The objectives of the thesis can be divided into three parts: one in which complexity and work effort in Windows 8 application development is evaluated, one in which the tools required to develop a VOD application is evaluated and finally implementing a Windows 8 application for VOD.

    A Windows 8 application was developed and the selected solution methods were documented. Documentation and knowledge acquired during the development phase was then used as a basis for the analysis and evaluation objectives. The result is a Windows 8 application meeting the objectives set for the development part followed by an analysis and evaluation answering the given issues.

    Matters that are central through the report are Microsoft, WinRT, VOD, PlayReady, Smooth Streaming, Windows 8 application Development, data caching and interface development in Windows 8.

  • 46.
    Ding, Christofer
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Evaluation of Recommender System2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Recommender System (RS) has become one of the most important component for many companies, such as YouTube and Amazon. A recommender system consists of a series of algorithms which predict and recommend products to users. This report covers the selection of many open source recommender system projects, and movie predictions are made using the selected recommender system. Based on the predictions, a comparison was made between precision and an improved precision algorithm.

    The selected RS uses singular value decomposition in the field of collaborative filtering. Based on the recommendation results produced by the RS, the comparison between precision and the improved precision algorithms showed that the result of improved precision is slightly higher than precision in different cutoff values and different dimensions of eigenvalues.

  • 47.
    Drejhammar, Frej
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Flow Java: declarative concurrency for Java2004Licentiate thesis, monograph (Other scientific)
    Abstract [en]

    This thesis presents the design, implementation, and evaluation of Flow Java, a programming language for the implementation of concurrent programs. Flow Java adds powerful programming abstractions for automatic synchronization of concurrent programs to Java. The abstractions added are single assignment variables (logic variables) and futures (read-only views of logic variables).

    The added abstractions conservatively extend Java with respect to types, parameter passing, and concurrency. Futures support secure concurrent abstractions and are essential for seamless integration of single assignment variables into Java. These abstractions allow for simple and concise implementation of high-level concurrent programming abstractions.

    Flow Java is implemented as a moderate extension to the GNU GCJ/libjava Java compiler and runtime environment. The extension is not speci c to a particular implementation, it could easily be incorporated into other Java implementations.

    The thesis presents three implementation strategies for single assignment variables. One strategy uses forwarding and dereferencing while the two others are variants of Taylor's scheme. Taylor's scheme represents logic variables as a circular list. The thesis presents a new adaptation of Taylor's scheme to a concurrent language using operating system threads.

    The Flow Java system is evaluated using standard Java benchmarks. Evaluation shows that in most cases the overhead incurred by the extensions is between 10% and 50%. For some pathological cases the runtime increases by up to 150%. Concurrent programs making use of Flow Java's automatic synchronization, generally perform as good as corresponding Java programs. In some cases Flow Java programs outperform Java programs by as much as 33%.

  • 48.
    Dubrova, Elena
    et al.
    KTH, School of Information and Communication Technology (ICT), Electronics and Embedded Systems.
    Näslund, Mats
    Ericsson AB.
    Carlsson, Gunnar
    Ericsson AB.
    Fornehed, John
    Ericsson AB.
    Smeets, Ben
    Ericsson AB.
    Two Countermeasures Against Hardware Trojans Exploiting Non-Zero Aliasing Probability of BIST2016In: Journal of Signal Processing Systems, ISSN 1939-8018, E-ISSN 1939-8115Article in journal (Refereed)
    Abstract [en]

    The threat of hardware Trojans has been widely recognized by academia, industry, and government agencies. A Trojan can compromise security of a system in spite of cryptographic protection. The damage caused by a Trojan may not be limited to a business or reputation, but could have a severe impact on public safety, national economy, or national security. An extremely stealthy way of implementing hardware Trojans has been presented by Becker et al. at CHES’2012. Their work have shown that it is possible to inject a Trojan in a random number generator compliant with FIPS 140-2 and NIST SP800-90 standards by exploiting non-zero aliasing probability of Logic Built-In-Self-Test (LBIST). In this paper, we present two methods for modifying LBIST to prevent such an attack. The first method makes test patterns dependent on a configurable key which is programed into a chip after the manufacturing stage. The second method uses a remote test management system which can execute LBIST using a different set of test patterns at each test cycle.

  • 49. Ebrahimi, M.
    et al.
    Daneshtalab, M.
    Sreejesh, N. P.
    Liljeberg, P.
    Tenhunen, Hannu
    KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS. University of Turku, Finland.
    Efficient network interface architecture for network-on-chips2009In: 2009 NORCHIP, 2009, article id 5397837Conference paper (Refereed)
    Abstract [en]

    In this paper, we present novel network interface architecture for on-chip networks to increase memory parallelism and to improve the resource utilization. The proposed architecture exploits AXI transaction based protocol to be compatible with existing IP cores. Experimental results with synthetic test case demonstrate that the proposed architecture outperforms the conventional architecture in term of latency.

  • 50.
    Ebrahimi, Masoumeh
    et al.
    KTH.
    Weldezion, Awet Yemane
    Hangofay AB, Stockholm, Sweden..
    Daneshtalab, Masoud
    Malardalen Univ, Vasteras, Sweden..
    NoD: Network-on-Die as a Standalone NoC for Heterogeneous Many-core Systems in 2.5D ICs2017In: 2017 19TH INTERNATIONAL SYMPOSIUM ON COMPUTER ARCHITECTURE AND DIGITAL SYSTEMS (CADS), IEEE , 2017, p. 28-33Conference paper (Refereed)
    Abstract [en]

    Due to a high cost of 3D IC process technology, the semiconductor industry is targeting 2.5D ICs with interposer as a fast and low-cost alternative to integrate dissimilar technologies. In this paper, we propose an independent network-on-chip die, called Network-on-Die (NoD), for 2.5D ICs that operates as a communication backbone for heterogeneous many-core systems on interposer. NoD is responsible for routing packets from a source router to a destination router, and the connections between routers and cores pass through the interposer. This technique eliminates the complexity of the routing algorithms in heterogeneous systems by turning the irregular form of NoC in 2.5D ICs into a regular/optimized one in NoD. The performance evaluation is verified through RTL simulations for a heterogeneous many-core system of varying die sizes and with asymmetric shapes. We provide the theoretical justification for our simulation results.

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