Browsing by Author "Timonen, Jussi"

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  • Applying security to user plane traffic in mobile communications networks
    (2002) Timonen, Jussi
     Helsinki University of Technology | Master's thesis
  • Crack dynamics and crack surfaces in elastic beam lattices
    (1998) Åström, Jan; Alava, Mikko J.; Timonen, Jussi
     School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The dynamics of propagating cracks is analyzed in elastic two-dimensional lattices of beams. At early times, inertia effects and static stress enhancement combine so that the crack-tip velocity is found to behave as t1/7. At late times a minimal crack-tip model reproduces the numerical simulation results. With no disorder and for fast loading, a “mirror-mist-mirror” crack-surface pattern emerges. Introduction of disorder leads, however, to the formation of the “mirror-mist-hackle”–type interface typical in many experimental situations.
  • Critical infrastructure visualization: Achieving situational awareness
    (2014) Rummukainen, Lauri
     Perustieteiden korkeakoulu | Master's thesis
    In a modern society, the complexity of various industries and their interdependencies has increased. This has led to a situation in which it has become increasingly difficult to monitor the status of all industry actors efficiently. However, during a large scale disaster, decision makers on various levels need to achieve situational awareness of the surrounding critical infrastructure to be able to prevent any faults propagating to their own systems. This thesis examines how the critical infrastructure could be visualized in order to achieve situational awareness of the state of the critical infrastructure. To deal with this problem, a user interface was constructed and evaluated on how well it supports situational awareness when monitoring critical infrastructure actors. The user interface consists of four displays visualizing information from the critical infrastructure in different ways. Different actors are categorized in 11 separate sectors, and events are used to present meaningful incidents. Past and current states, together with geographical distribution and logical dependencies, are presented to the user. The current states are visualized as segmented circles to represent event categories. Geographical distribution of assets is displayed with a well-known map tool. Logical dependencies are presented in a simple directed graph, and users also have a timeline to review past events. The objective of the user interface is to provide an easily understandable overview of the critical infrastructure status. Therefore, testing methods, such as a visual walkthrough, an informal walkthrough, System Usability Scale (SUS), and the Situation Awareness Global Assessment Technique (SAGAT), were used in the evaluation of the user interface. Results showed that users were able to obtain an understanding of the current state of critical infrastructure, and the usability of the user interface was rated as good. In particular, the designated display for the critical infrastructure overview and the timeline were found to be efficient.
  • Common Operating Picture of Critical Infrastructure: System Design and Implementation
    (2014-06-16) Lääperi, Lauri
     Sähkötekniikan korkeakoulu | Master's thesis
    Moderni yhteiskunta on hyvin riippuvainen kriittisen infrastruktuurin tarjoamista palveluista, kuten sähköstä, vedestä ja tietoliikenteestä. Reaaliaikainen kriittisen infrastruktuurin yhteinen tilannekuva, jonka avulla useat eri päätöksentekijät pystyvät tekemään järkeviä kriittistä infrastruktuuria koskevia päätöksiä, on vaatimus häiriötilanteista palautumisen johtamiselle ja ohjaamiselle. Lisäksi kriittisen infrastruktuurin sisäiset riippuvuudet ovat oleellisia päätöksentekijän tilannetietoisuuden saavuttamiseksi johon tarvitaan ymmärrys sekä kriittisen infrastruktuurin nykyisestä että tulevasta tilasta. Tässä diplomityössä esitetään vaatimukset ja arkkitehtuuri järjestelmälle, joka kykenee tarjoamaan kansallista tilannekuvaa, sekä ehdotetaan menetelmiä järjestelmän toteuttamiseen. Tilannekuvajärjestelmän vaatimukset määritellään kriittisen infrastruktuurin rakenteen perusteella sekä toimintaympäristön ymmärtämisen jälkeen. Tilannekuva tarjotaan joustavan agenttipohjaisen viestinvälittäjä arkkitehtuurin kautta, joka täyttää ympäristön asettamat vaatimukset. Arkkitehtuurin osat ovat suunniteltu JDL (Joint Directors of Laboratories) datafuusiomallin mukaan, mikä mahdollistaa erilaisten kriittisen infrastruktuuri järjestelmien integraation. Geneerinen agenttikomponentti muokataan kohdejärjestelmäkohtaisesti tuottamaan tapahtumia kolmelle erilliselle analysointi komponentille, jotka muodostavat merkityksellisiä tapahtumaolioita, ajankohtaisen tilan ja tulevaisuuden ennusteen kerätystä tiedosta. Toteutettua järjestelmän prototyyppiä käytetään testaamaan ja arvioimaan tilannekuvajärjestelmän arkkitehtuuria. Tosimaailman dataa tunkeutujan havaitsemisjärjestelmästä (IDS) ja SCADA (Supervisory Control and Data Acquisition) järjestelmästä käytetään testaamaan erilaisten järjestelmien integraatiota. Toteutetun järjestelmän suorituskykyä mittaamalla voitiin todeta, että toteutettu arkkitehtuuri täyttää järjestelmälle asetetut vaatimukset.
  • Localization Services for Online Common Operational Picture and Situation Awareness
    (2013) Björkbom, Mikael; Timonen, Jussi; Yigitler, Huseyin; Kaltiokallio, Ossi; Garcia, Jose Vallet; Myrsky, Matthieu; Saarinen, Jari; Korkalainen, Marko; Cuhac, Caner; Jäntti, Riku; Virrankoski, Reino; Vankka, Jouko; Koivo, Heikki
     School of Electrical Engineering | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Many operations, be they military, police, rescue, or other field operations, require localization services and online situation awareness to make them effective. Questions such as how many people are inside a building and their locations are essential. In this paper, an online localization and situation awareness system is presented, called Mobile Urban Situation Awareness System (MUSAS), for gathering and maintaining localization information, to form a common operational picture. The MUSAS provides multiple localization services, as well as visualization of other sensor data, in a common frame of reference. The information and common operational picture of the system is conveyed to all parties involved in the operation, the field team, and people in the command post. In this paper, a general system architecture for enabling localization based situation awareness is designed and the MUSAS system solution is presented. The developed subsystem components and forming of the common operational picture are summarized, and the future potential of the system for various scenarios is discussed. In the demonstration, the MUSAS is deployed to an unknown building, in an ad hoc fashion, to provide situation awareness in an urban indoor military operation.
  • Propagation and kinetic roughening of wave fronts in disordered lattices
    (1997) Åström, Jan; Kellomäki, Markku; Alava, Mikko J.; Timonen, Jussi
     School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The dynamics of a wave front propagating in diluted square lattices of elastic beams is analyzed. We concentrate on the propagation of the first maximum of a semi-infinite wave train. Two different limits are found for the velocity depending on the bending stiffness of the beams. If it vanishes, a one-dimensional chain model is derived for the velocity and the amplitude is found to decrease exponentially. The first maximum is localized and the average width of the wave front is always finite. For very stiff beams an effective-medium model gives the correct velocity and the amplitude of the first maximum decays according to a power law. No localization of the first maximum is observed in the simulations. In this limit scaling arguments based on Huygen’s principle suggest a growth exponent of 1/2, and a roughness exponent of 2/3. The growth exponent fits the simulation data well, but a considerably lower roughness exponent (0.5) is obtained. There is a crossover region for the bending stiffness, wherein the wave-front behavior cannot be explained by these limiting cases.
  • Propagation and kinetic roughening of wave fronts in disordered lattices
    (1997-11) Åström, Jan; Kellomäki, Markku; Alava, Mikko; Timonen, Jussi
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The dynamics of a wave front propagating in diluted square lattices of elastic beams is analyzed. We concentrate on the propagation of the first maximum of a semi-infinite wave train. Two different limits are found for the velocity depending on the bending stiffness of the beams. If it vanishes, a one-dimensional chain model is derived for the velocity and the amplitude is found to decrease exponentially. The first maximum is localized and the average width of the wave front is always finite. For very stiff beams an effective-medium model gives the correct velocity and the amplitude of the first maximum decays according to a power law. No localization of the first maximum is observed in the simulations. In this limit scaling arguments based on Huygen's principle suggest a growth exponent of 1/2, and a roughness exponent of 2/3. The growth exponent fits the simulation data well, but a considerably lower roughness exponent (0.5) is obtained. There is a crossover region for the bending stiffness, wherein the wave-front behavior cannot be explained by these limiting cases.